xref: /external/wayland-protocols/wayland_protocol_codegen.go

// Copyright (C) 2017 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

/*
Package wayland_protocol defines an plugin module for the Soong build system,
which makes it easier to generate code from a list of Wayland protocol files.

The primary build module is "wayland_protocol_codegen", which takes a list of
protocol files, and runs a configurable code-generation tool to generate
source code for each one. There is also a "wayland_protocol_codegen_defaults"
for setting common properties.

This package is substantially similar to the base "android/soong/genrule"
package, which was originally used for inspiration for this one, and has
been recently restructured so that it can be kept in sync with a tool like
"vimdiff" to keep things in sync as needed.

However this build system plugin will not be needed in the future, as
evidenced by some of the other files that have been added as part of the
last big sync-up. In the future, Android will be built with Bazel, and it
is much simpler there to define our own local version of "gensrcs" that
implements the functionality we need See bazel/gensrcs.bzl for it.

Notable differences:

  - This package implements a more powerful template mechanism for specifying
    what output path/filename should be used for each source filename. The
    genrule package only allows the extension on each source filename to be
    replaced.

  - This package drops support for depfiles, after observing comments that
    they are problematic in the genrule package sources.

  - This package drops "Extra" and "CmdModifier" from the public Module
    structure, as this module is not expected to be extended.

  - This package drops "rule" from the public Module structure, as it was
    unused but present in genrule.

# Usage

	wayland_protocol_codegen {
		// A standard target name.
		name: "wayland_extension_protocol_sources",

		// A simple template for generating output filenames.
		output: "$(in).c"

		// The command line template. See "Cmd".
		cmd: "$(location wayland_scanner) code < $(in) > $(out)",

		// Protocol source files for the expansion.
		srcs: [":wayland_extension_protocols"],

		// Any buildable binaries to use as tools
		tools: ["wayland_scanner"],

		// Any source files to be used  (scripts, template files)
		tools_files: [],
	}
*/
package soong_wayland_protocol_codegen

import (
	"fmt"
	"strconv"
	"strings"

	"github.com/google/blueprint"
	"github.com/google/blueprint/bootstrap"
	"github.com/google/blueprint/proptools"

	"android/soong/android"
	"android/soong/bazel"
	"android/soong/bazel/cquery"
	"android/soong/genrule"
	"path/filepath"
)

func init() {
	registerCodeGenBuildComponents(android.InitRegistrationContext)
}

func registerCodeGenBuildComponents(ctx android.RegistrationContext) {
	ctx.RegisterModuleType("wayland_protocol_codegen_defaults", defaultsFactory)

	ctx.RegisterModuleType("wayland_protocol_codegen", codegenFactory)

	ctx.FinalDepsMutators(func(ctx android.RegisterMutatorsContext) {
		ctx.BottomUp("wayland_protocol_codegen_tool_deps", toolDepsMutator).Parallel()
	})
}

var (
	pctx = android.NewPackageContext("android/soong/external/wayland_protocol_codegen")

	// Used by wayland_protocol_codegen when there is more than 1 shard to merge the outputs
	// of each shard into a zip file.
	gensrcsMerge = pctx.AndroidStaticRule("wayland_protocol_codegenMerge", blueprint.RuleParams{
		Command:        "${soongZip} -o ${tmpZip} @${tmpZip}.rsp && ${zipSync} -d ${genDir} ${tmpZip}",
		CommandDeps:    []string{"${soongZip}", "${zipSync}"},
		Rspfile:        "${tmpZip}.rsp",
		RspfileContent: "${zipArgs}",
	}, "tmpZip", "genDir", "zipArgs")
)

func init() {
	pctx.Import("android/soong/android")

	pctx.HostBinToolVariable("soongZip", "soong_zip")
	pctx.HostBinToolVariable("zipSync", "zipsync")
}

type hostToolDependencyTag struct {
	blueprint.BaseDependencyTag
	android.LicenseAnnotationToolchainDependencyTag
	label string
}

func (t hostToolDependencyTag) AllowDisabledModuleDependency(target android.Module) bool {
	// Allow depending on a disabled module if it's replaced by a prebuilt
	// counterpart. We get the prebuilt through android.PrebuiltGetPreferred in
	// GenerateAndroidBuildActions.
	return target.IsReplacedByPrebuilt()
}

var _ android.AllowDisabledModuleDependency = (*hostToolDependencyTag)(nil)

type generatorProperties struct {
	// The command to run on one or more input files. Cmd supports
	// substitution of a few variables (the actual substitution is implemented
	// in GenerateAndroidBuildActions below)
	//
	// Available variables for substitution:
	//
	//	- $(location)
	//		the path to the first entry in tools or tool_files
	//	- $(location <label>)
	//		the path to the tool, tool_file, input or output with name <label>. Use
	//		$(location) if <label> refers to a rule that outputs exactly one file.
	//	- $(locations <label>)
	//		the paths to the tools, tool_files, inputs or outputs with name
	//		<label>. Use $(locations) if <label> refers to a rule that outputs two
	//		or more files.
	//	- $(in)
	//		one or more input files
	//	- $(out)
	//		a single output file
	//	- $(genDir)
	//		the sandbox directory for this tool; contains $(out)
	//	- $$
	//		a literal '$'
	//
	// All files used must be declared as inputs (to ensure proper up-to-date
	// checks). Use "$(in)" directly in Cmd to ensure that all inputs used are
	// declared.
	Cmd *string

	// name of the modules (if any) that produces the host executable. Leave
	// empty for prebuilts or scripts that do not need a module to build them.
	Tools []string

	// Local source files that are used as scripts or other input files needed
	// by a tool.
	Tool_files []string `android:"path"`

	// List of directories to export generated headers from.
	Export_include_dirs []string

	// List of input files.
	Srcs []string `android:"path,arch_variant"`

	// Input files to exclude.
	Exclude_srcs []string `android:"path,arch_variant"`
}

type Module struct {
	android.ModuleBase
	android.DefaultableModuleBase
	android.BazelModuleBase
	android.ApexModuleBase

	android.ImageInterface

	properties generatorProperties

	taskGenerator taskFunc

	rawCommands []string

	exportedIncludeDirs android.Paths

	outputFiles android.Paths
	outputDeps  android.Paths

	subName string
	subDir  string

	// Collect the module directory for IDE info in java/jdeps.go.
	modulePaths []string
}

// Ensure Module implements the android.MixedBuildBuildable interface.
var _ android.MixedBuildBuildable = (*Module)(nil)

type taskFunc func(ctx android.ModuleContext, rawCommand string, srcFiles android.Paths) []generateTask

type generateTask struct {
	in     android.Paths
	out    android.WritablePaths
	copyTo android.WritablePaths
	genDir android.WritablePath
	cmd    string

	shard  int
	shards int
}

// Part of genrule.SourceFileGenerator.
// Returns the list of generated source files.
func (g *Module) GeneratedSourceFiles() android.Paths {
	return g.outputFiles
}

// Part of genrule.SourceFileGenerator.
// Returns the list of input source files.
func (g *Module) Srcs() android.Paths {
	return append(android.Paths{}, g.outputFiles...)
}

// Part of genrule.SourceFileGenerator.
// Returns the list of the list of exported include paths.
func (g *Module) GeneratedHeaderDirs() android.Paths {
	return g.exportedIncludeDirs
}

// Part of genrule.SourceFileGenerator.
// Returns the list of files to be used as dependencies when using
// GeneratedHeaderDirs
func (g *Module) GeneratedDeps() android.Paths {
	return g.outputDeps
}

// Part of android.OutputFileProducer.
// Returns the list of output files matching a tag, or an error if there is no
// match.
func (g *Module) OutputFiles(tag string) (android.Paths, error) {
	if tag == "" {
		return append(android.Paths{}, g.outputFiles...), nil
	}
	// otherwise, tag should match one of outputs
	for _, outputFile := range g.outputFiles {
		if outputFile.Rel() == tag {
			return android.Paths{outputFile}, nil
		}
	}
	return nil, fmt.Errorf("unsupported module reference tag %q", tag)
}

// Ensure Module implements the genrule.SourceFileGenerator interface.
var _ genrule.SourceFileGenerator = (*Module)(nil)

// Ensure Module implements the android.SourceFileProducer interface.
var _ android.SourceFileProducer = (*Module)(nil)

// Ensure Module implements the android.OutputFileProducer interface.
var _ android.OutputFileProducer = (*Module)(nil)

func toolDepsMutator(ctx android.BottomUpMutatorContext) {
	if g, ok := ctx.Module().(*Module); ok {
		for _, tool := range g.properties.Tools {
			tag := hostToolDependencyTag{label: tool}
			if m := android.SrcIsModule(tool); m != "" {
				tool = m
			}
			ctx.AddFarVariationDependencies(ctx.Config().BuildOSTarget.Variations(), tag, tool)
		}
	}
}

// Part of android.MixedBuildBuildable.
// Allow this module to be a bridge between Bazel and Soong. Fills in Soong
// properties for the module from the Bazel cquery, so that other Soong
// modules can depend on the module when it was actually built by Bazel.
func (g *Module) ProcessBazelQueryResponse(ctx android.ModuleContext) {
	g.generateCommonBuildActions(ctx)

	// Get the list of output files that Bazel generates for the target.
	label := g.GetBazelLabel(ctx, g)
	bazelCtx := ctx.Config().BazelContext
	filePaths, err := bazelCtx.GetOutputFiles(label, android.GetConfigKey(ctx))
	if err != nil {
		ctx.ModuleErrorf(err.Error())
		return
	}

	// Convert to android.Paths, and also form the set of include directories
	// that might be needed for those paths.
	var bazelOutputFiles android.Paths
	exportIncludeDirs := map[string]bool{}
	for _, bazelOutputFile := range filePaths {
		bazelOutputFiles = append(bazelOutputFiles,
			android.PathForBazelOutRelative(ctx, ctx.ModuleDir(), bazelOutputFile))
		exportIncludeDirs[filepath.Dir(bazelOutputFile)] = true
	}

	// Set the Soong module properties to refer to the Bazel files
	g.outputFiles = bazelOutputFiles
	g.outputDeps = bazelOutputFiles
	for includePath, _ := range exportIncludeDirs {
		g.exportedIncludeDirs = append(g.exportedIncludeDirs,
			android.PathForBazelOut(ctx, includePath))
	}
}

// Part of android.Module.
// Generates all the rules and builds commands used by this module instance.
func (g *Module) generateCommonBuildActions(ctx android.ModuleContext) {
	g.subName = ctx.ModuleSubDir()

	// Collect the module directory for IDE info in java/jdeps.go.
	g.modulePaths = append(g.modulePaths, ctx.ModuleDir())

	if len(g.properties.Export_include_dirs) > 0 {
		for _, dir := range g.properties.Export_include_dirs {
			g.exportedIncludeDirs = append(g.exportedIncludeDirs,
				android.PathForModuleGen(ctx, g.subDir, ctx.ModuleDir(), dir))
		}
	} else {
		g.exportedIncludeDirs = append(g.exportedIncludeDirs, android.PathForModuleGen(ctx, g.subDir))
	}

	locationLabels := map[string]location{}
	firstLabel := ""

	addLocationLabel := func(label string, loc location) {
		if firstLabel == "" {
			firstLabel = label
		}
		if _, exists := locationLabels[label]; !exists {
			locationLabels[label] = loc
		} else {
			ctx.ModuleErrorf("multiple locations for label %q: %q and %q (do you have duplicate srcs entries?)",
				label, locationLabels[label], loc)
		}
	}

	var tools android.Paths
	var packagedTools []android.PackagingSpec
	if len(g.properties.Tools) > 0 {
		seenTools := make(map[string]bool)

		ctx.VisitDirectDepsBlueprint(func(module blueprint.Module) {
			switch tag := ctx.OtherModuleDependencyTag(module).(type) {
			case hostToolDependencyTag:
				tool := ctx.OtherModuleName(module)
				if m, ok := module.(android.Module); ok {
					// Necessary to retrieve any prebuilt replacement for the tool, since
					// toolDepsMutator runs too late for the prebuilt mutators to have
					// replaced the dependency.
					module = android.PrebuiltGetPreferred(ctx, m)
				}

				switch t := module.(type) {
				case android.HostToolProvider:
					// A HostToolProvider provides the path to a tool, which will be copied
					// into the sandbox.
					if !t.(android.Module).Enabled() {
						if ctx.Config().AllowMissingDependencies() {
							ctx.AddMissingDependencies([]string{tool})
						} else {
							ctx.ModuleErrorf("depends on disabled module %q", tool)
						}
						return
					}
					path := t.HostToolPath()
					if !path.Valid() {
						ctx.ModuleErrorf("host tool %q missing output file", tool)
						return
					}
					if specs := t.TransitivePackagingSpecs(); specs != nil {
						// If the HostToolProvider has PackgingSpecs, which are definitions of the
						// required relative locations of the tool and its dependencies, use those
						// instead.  They will be copied to those relative locations in the sbox
						// sandbox.
						packagedTools = append(packagedTools, specs...)
						// Assume that the first PackagingSpec of the module is the tool.
						addLocationLabel(tag.label, packagedToolLocation{specs[0]})
					} else {
						tools = append(tools, path.Path())
						addLocationLabel(tag.label, toolLocation{android.Paths{path.Path()}})
					}
				case bootstrap.GoBinaryTool:
					// A GoBinaryTool provides the install path to a tool, which will be copied.
					p := android.PathForGoBinary(ctx, t)
					tools = append(tools, p)
					addLocationLabel(tag.label, toolLocation{android.Paths{p}})
				default:
					ctx.ModuleErrorf("%q is not a host tool provider", tool)
					return
				}

				seenTools[tag.label] = true
			}
		})

		// If AllowMissingDependencies is enabled, the build will not have stopped when
		// AddFarVariationDependencies was called on a missing tool, which will result in nonsensical
		// "cmd: unknown location label ..." errors later.  Add a placeholder file to the local label.
		// The command that uses this placeholder file will never be executed because the rule will be
		// replaced with an android.Error rule reporting the missing dependencies.
		if ctx.Config().AllowMissingDependencies() {
			for _, tool := range g.properties.Tools {
				if !seenTools[tool] {
					addLocationLabel(tool, errorLocation{"***missing tool " + tool + "***"})
				}
			}
		}
	}

	if ctx.Failed() {
		return
	}

	for _, toolFile := range g.properties.Tool_files {
		paths := android.PathsForModuleSrc(ctx, []string{toolFile})
		tools = append(tools, paths...)
		addLocationLabel(toolFile, toolLocation{paths})
	}

	includeDirInPaths := ctx.DeviceConfig().BuildBrokenInputDir(g.Name())
	var srcFiles android.Paths
	for _, in := range g.properties.Srcs {
		paths, missingDeps := android.PathsAndMissingDepsRelativeToModuleSourceDir(android.SourceInput{
			Context: ctx, Paths: []string{in}, ExcludePaths: g.properties.Exclude_srcs, IncludeDirs: includeDirInPaths,
		})
		if len(missingDeps) > 0 {
			if !ctx.Config().AllowMissingDependencies() {
				panic(fmt.Errorf("should never get here, the missing dependencies %q should have been reported in DepsMutator",
					missingDeps))
			}

			// If AllowMissingDependencies is enabled, the build will not have stopped when
			// the dependency was added on a missing SourceFileProducer module, which will result in nonsensical
			// "cmd: label ":..." has no files" errors later.  Add a placeholder file to the local label.
			// The command that uses this placeholder file will never be executed because the rule will be
			// replaced with an android.Error rule reporting the missing dependencies.
			ctx.AddMissingDependencies(missingDeps)
			addLocationLabel(in, errorLocation{"***missing srcs " + in + "***"})
		} else {
			srcFiles = append(srcFiles, paths...)
			addLocationLabel(in, inputLocation{paths})
		}
	}

	var copyFrom android.Paths
	var outputFiles android.WritablePaths
	var zipArgs strings.Builder

	cmd := proptools.String(g.properties.Cmd)

	tasks := g.taskGenerator(ctx, cmd, srcFiles)
	if ctx.Failed() {
		return
	}

	for _, task := range tasks {
		if len(task.out) == 0 {
			ctx.ModuleErrorf("must have at least one output file")
			return
		}

		// Pick a unique path outside the task.genDir for the sbox manifest textproto,
		// a unique rule name, and the user-visible description.
		manifestName := "wayland_protocol_codegen.sbox.textproto"
		desc := "generate"
		name := "generator"
		if task.shards > 0 {
			manifestName = "wayland_protocol_codegen_" + strconv.Itoa(task.shard) + ".sbox.textproto"
			desc += " " + strconv.Itoa(task.shard)
			name += strconv.Itoa(task.shard)
		} else if len(task.out) == 1 {
			desc += " " + task.out[0].Base()
		}

		manifestPath := android.PathForModuleOut(ctx, manifestName)

		// Use a RuleBuilder to create a rule that runs the command inside an sbox sandbox.
		rule := android.NewRuleBuilder(pctx, ctx).Sbox(task.genDir, manifestPath).SandboxTools()
		cmd := rule.Command()

		for _, out := range task.out {
			addLocationLabel(out.Rel(), outputLocation{out})
		}

		rawCommand, err := android.Expand(task.cmd, func(name string) (string, error) {
			// Report the error directly without returning an error to android.Expand to catch multiple errors in a
			// single run
			reportError := func(fmt string, args ...interface{}) (string, error) {
				ctx.PropertyErrorf("cmd", fmt, args...)
				return "SOONG_ERROR", nil
			}

			// Apply shell escape to each cases to prevent source file paths containing $ from being evaluated in shell
			switch name {
			case "location":
				if len(g.properties.Tools) == 0 && len(g.properties.Tool_files) == 0 {
					return reportError("at least one `tools` or `tool_files` is required if $(location) is used")
				}
				loc := locationLabels[firstLabel]
				paths := loc.Paths(cmd)
				if len(paths) == 0 {
					return reportError("default label %q has no files", firstLabel)
				} else if len(paths) > 1 {
					return reportError("default label %q has multiple files, use $(locations %s) to reference it",
						firstLabel, firstLabel)
				}
				return proptools.ShellEscape(paths[0]), nil
			case "in":
				return strings.Join(proptools.ShellEscapeList(cmd.PathsForInputs(srcFiles)), " "), nil
			case "out":
				var sandboxOuts []string
				for _, out := range task.out {
					sandboxOuts = append(sandboxOuts, cmd.PathForOutput(out))
				}
				return strings.Join(proptools.ShellEscapeList(sandboxOuts), " "), nil
			case "genDir":
				return proptools.ShellEscape(cmd.PathForOutput(task.genDir)), nil
			default:
				if strings.HasPrefix(name, "location ") {
					label := strings.TrimSpace(strings.TrimPrefix(name, "location "))
					if loc, ok := locationLabels[label]; ok {
						paths := loc.Paths(cmd)
						if len(paths) == 0 {
							return reportError("label %q has no files", label)
						} else if len(paths) > 1 {
							return reportError("label %q has multiple files, use $(locations %s) to reference it",
								label, label)
						}
						return proptools.ShellEscape(paths[0]), nil
					} else {
						return reportError("unknown location label %q is not in srcs, out, tools or tool_files.", label)
					}
				} else if strings.HasPrefix(name, "locations ") {
					label := strings.TrimSpace(strings.TrimPrefix(name, "locations "))
					if loc, ok := locationLabels[label]; ok {
						paths := loc.Paths(cmd)
						if len(paths) == 0 {
							return reportError("label %q has no files", label)
						}
						return proptools.ShellEscape(strings.Join(paths, " ")), nil
					} else {
						return reportError("unknown locations label %q is not in srcs, out, tools or tool_files.", label)
					}
				} else {
					return reportError("unknown variable '$(%s)'", name)
				}
			}
		})

		if err != nil {
			ctx.PropertyErrorf("cmd", "%s", err.Error())
			return
		}

		g.rawCommands = append(g.rawCommands, rawCommand)

		cmd.Text(rawCommand)
		cmd.ImplicitOutputs(task.out)
		cmd.Implicits(task.in)
		cmd.ImplicitTools(tools)
		cmd.ImplicitPackagedTools(packagedTools)

		// Create the rule to run the genrule command inside sbox.
		rule.Build(name, desc)

		if len(task.copyTo) > 0 {
			// If copyTo is set, multiple shards need to be copied into a single directory.
			// task.out contains the per-shard paths, and copyTo contains the corresponding
			// final path.  The files need to be copied into the final directory by a
			// single rule so it can remove the directory before it starts to ensure no
			// old files remain.  zipsync already does this, so build up zipArgs that
			// zip all the per-shard directories into a single zip.
			outputFiles = append(outputFiles, task.copyTo...)
			copyFrom = append(copyFrom, task.out.Paths()...)
			zipArgs.WriteString(" -C " + task.genDir.String())
			zipArgs.WriteString(android.JoinWithPrefix(task.out.Strings(), " -f "))
		} else {
			outputFiles = append(outputFiles, task.out...)
		}
	}

	if len(copyFrom) > 0 {
		// Create a rule that zips all the per-shard directories into a single zip and then
		// uses zipsync to unzip it into the final directory.
		ctx.Build(pctx, android.BuildParams{
			Rule:        gensrcsMerge,
			Implicits:   copyFrom,
			Outputs:     outputFiles,
			Description: "merge shards",
			Args: map[string]string{
				"zipArgs": zipArgs.String(),
				"tmpZip":  android.PathForModuleGen(ctx, g.subDir+".zip").String(),
				"genDir":  android.PathForModuleGen(ctx, g.subDir).String(),
			},
		})
	}

	g.outputFiles = outputFiles.Paths()
}

func (g *Module) GenerateAndroidBuildActions(ctx android.ModuleContext) {
	g.generateCommonBuildActions(ctx)

	// When there are less than six outputs, we directly give those as the
	// output dependency for this module. However, if there are more outputs,
	// we inject a phony target. This potentially saves space in the generated
	// ninja file, as well as simplifying any visualizations of the dependency
	// graph.
	if len(g.outputFiles) <= 6 {
		g.outputDeps = g.outputFiles
	} else {
		phonyFile := android.PathForModuleGen(ctx, "genrule-phony")
		ctx.Build(pctx, android.BuildParams{
			Rule:   blueprint.Phony,
			Output: phonyFile,
			Inputs: g.outputFiles,
		})
		g.outputDeps = android.Paths{phonyFile}
	}
}

// Part of android.MixedBuildBuildable.
// Queues up Bazel cquery requests related to this module.
func (g *Module) QueueBazelCall(ctx android.BaseModuleContext) {
	bazelCtx := ctx.Config().BazelContext
	bazelCtx.QueueBazelRequest(g.GetBazelLabel(ctx, g), cquery.GetOutputFiles,
		android.GetConfigKey(ctx))
}

// Part of android.MixedBuildBuildable.
// Returns true if Bazel can and should build this module in a mixed build.
func (g *Module) IsMixedBuildSupported(ctx android.BaseModuleContext) bool {
	return true
}

// Part of android.IDEInfo.
// Collect information for opening IDE project files in java/jdeps.go.
func (g *Module) IDEInfo(dpInfo *android.IdeInfo) {
	dpInfo.Srcs = append(dpInfo.Srcs, g.Srcs().Strings()...)
	for _, src := range g.properties.Srcs {
		if strings.HasPrefix(src, ":") {
			src = strings.Trim(src, ":")
			dpInfo.Deps = append(dpInfo.Deps, src)
		}
	}
	dpInfo.Paths = append(dpInfo.Paths, g.modulePaths...)
}

// Ensure Module implements android.ApexModule
// Note: gensrcs implements it but it's possible we do not actually need to.
var _ android.ApexModule = (*Module)(nil)

// Part of android.ApexModule.
func (g *Module) ShouldSupportSdkVersion(ctx android.BaseModuleContext,
	sdkVersion android.ApiLevel) error {
	// Because generated outputs are checked by client modules(e.g. cc_library, ...)
	// we can safely ignore the check here.
	return nil
}

func generatorFactory(taskGenerator taskFunc, props ...interface{}) *Module {
	module := &Module{
		taskGenerator: taskGenerator,
	}

	module.AddProperties(props...)
	module.AddProperties(&module.properties)

	module.ImageInterface = noopImageInterface{}

	return module
}

type noopImageInterface struct{}

func (x noopImageInterface) ImageMutatorBegin(android.BaseModuleContext)                 {}
func (x noopImageInterface) CoreVariantNeeded(android.BaseModuleContext) bool            { return false }
func (x noopImageInterface) RamdiskVariantNeeded(android.BaseModuleContext) bool         { return false }
func (x noopImageInterface) VendorRamdiskVariantNeeded(android.BaseModuleContext) bool   { return false }
func (x noopImageInterface) DebugRamdiskVariantNeeded(android.BaseModuleContext) bool    { return false }
func (x noopImageInterface) RecoveryVariantNeeded(android.BaseModuleContext) bool        { return false }
func (x noopImageInterface) ExtraImageVariations(ctx android.BaseModuleContext) []string { return nil }
func (x noopImageInterface) SetImageVariation(ctx android.BaseModuleContext, variation string, module android.Module) {
}

// Constructs a Module for handling the code generation.
func newCodegen() *Module {
	properties := &codegenProperties{}

	// finalSubDir is the name of the subdirectory that output files will be generated into.
	// It is used so that per-shard directories can be placed alongside it an then finally
	// merged into it.
	const finalSubDir = "wayland_protocol_codegen"

	// Code generation commands are sharded so that up to this many files
	// are generated as part of one sandbox process.
	const defaultShardSize = 100

	taskGenerator := func(ctx android.ModuleContext, rawCommand string, srcFiles android.Paths) []generateTask {
		shardSize := defaultShardSize

		if len(srcFiles) == 0 {
			ctx.ModuleErrorf("must have at least one source file")
			return []generateTask{}
		}

		// wayland_protocol_codegen rules can easily hit command line limits by
		// repeating the command for every input file.  Shard the input files into
		// groups.
		shards := android.ShardPaths(srcFiles, shardSize)
		var generateTasks []generateTask

		distinctOutputs := make(map[string]android.Path)

		for i, shard := range shards {
			var commands []string
			var outFiles android.WritablePaths
			var copyTo android.WritablePaths

			// When sharding is enabled (i.e. len(shards) > 1), the sbox rules for each
			// shard will be write to their own directories and then be merged together
			// into finalSubDir.  If sharding is not enabled (i.e. len(shards) == 1),
			// the sbox rule will write directly to finalSubDir.
			genSubDir := finalSubDir
			if len(shards) > 1 {
				genSubDir = strconv.Itoa(i)
			}

			genDir := android.PathForModuleGen(ctx, genSubDir)
			// NOTE: This TODO is copied from gensrcs, as applies here too.
			// TODO(ccross): this RuleBuilder is a hack to be able to call
			// rule.Command().PathForOutput.  Replace this with passing the rule into the
			// generator.
			rule := android.NewRuleBuilder(pctx, ctx).Sbox(genDir, nil).SandboxTools()

			for _, in := range shard {
				outFileRaw := expandOutputPath(ctx, *properties, in)

				if conflictWith, hasKey := distinctOutputs[outFileRaw]; hasKey {
					ctx.ModuleErrorf("generation conflict: both '%v' and '%v' generate '%v'",
						conflictWith.String(), in.String(), outFileRaw)
				}

				distinctOutputs[outFileRaw] = in

				outFile := android.PathForModuleGen(ctx, finalSubDir, outFileRaw)

				// If sharding is enabled, then outFile is the path to the output file in
				// the shard directory, and copyTo is the path to the output file in the
				// final directory.
				if len(shards) > 1 {
					shardFile := android.PathForModuleGen(ctx, genSubDir, outFileRaw)
					copyTo = append(copyTo, outFile)
					outFile = shardFile
				}

				outFiles = append(outFiles, outFile)

				// pre-expand the command line to replace $in and $out with references to
				// a single input and output file.
				command, err := android.Expand(rawCommand, func(name string) (string, error) {
					switch name {
					case "in":
						return in.String(), nil
					case "out":
						return rule.Command().PathForOutput(outFile), nil
					default:
						return "$(" + name + ")", nil
					}
				})
				if err != nil {
					ctx.PropertyErrorf("cmd", err.Error())
				}

				// escape the command in case for example it contains '#', an odd number of '"', etc
				command = fmt.Sprintf("bash -c %v", proptools.ShellEscape(command))
				commands = append(commands, command)
			}
			fullCommand := strings.Join(commands, " && ")

			generateTasks = append(generateTasks, generateTask{
				in:     shard,
				out:    outFiles,
				copyTo: copyTo,
				genDir: genDir,
				cmd:    fullCommand,
				shard:  i,
				shards: len(shards),
			})
		}

		return generateTasks
	}

	g := generatorFactory(taskGenerator, properties)
	g.subDir = finalSubDir
	return g
}

// Factory for code generation modules
func codegenFactory() android.Module {
	m := newCodegen()
	android.InitAndroidModule(m)
	android.InitBazelModule(m)
	android.InitDefaultableModule(m)
	return m
}

// The custom properties specific to this code generation module.
type codegenProperties struct {
	// The string to prepend to every protocol filename to generate the
	// corresponding output filename. The empty string by default.
	// Deprecated. Prefer "Output" instead.
	Prefix *string

	// The suffix to append to every protocol filename to generate the
	// corresponding output filename. The empty string by default.
	// Deprecated. Prefer "Output" instead.
	Suffix *string

	// The output filename template.
	//
	// This template string allows the output file name to be generated for
	// each source file, using some limited properties of the source file.
	//
	//	$(in:base): The base filename, no path or extension
	//	$(in:base.ext): The filename, no path
	//	$(in:path/base): The filename with path but no extension
	//	$(in:path/base.ext): The full source filename
	//	$(in): An alias for $(in:base) for the base filename, no extension
	//
	// Note that the path that is maintained is the relative path used when
	// including the source in an Android.bp file.
	//
	// The template allows arbitrary prefixes and suffixes to be added to the
	// output filename. For example, "a_$(in).d" would take an source filename
	// of "b.c" and turn it into "a_b.d".
	//
	// The output template does not have to generate a unique filename,
	// however the implementation will raise an error if the same output file
	// is generated by more than one source file.
	Output *string
}

// Expands the output path pattern to form the output path for the given
// input path.
func expandOutputPath(ctx android.ModuleContext, properties codegenProperties, in android.Path) string {
	template := proptools.String(properties.Output)
	if len(template) == 0 {
		prefix := proptools.String(properties.Prefix)
		suffix := proptools.String(properties.Suffix)
		return prefix + removeExtension(in.Base()) + suffix
	}

	outPath, _ := android.Expand(template, func(name string) (string, error) {
		// Report the error directly without returning an error to
		// android.Expand to catch multiple errors in a single run.
		reportError := func(fmt string, args ...interface{}) (string, error) {
			ctx.PropertyErrorf("output", fmt, args...)
			return "EXPANSION_ERROR", nil
		}

		switch name {
		case "in":
			return removeExtension(in.Base()), nil
		case "in:base":
			return removeExtension(in.Base()), nil
		case "in:base.ext":
			return in.Base(), nil
		case "in:path/base":
			return removeExtension(in.Rel()), nil
		case "in:path/base.ext":
			return in.Rel(), nil
		default:
			return reportError("unknown variable '$(%s)'", name)
		}
	})

	return outPath
}

// Removes any extension from the final component of a path.
func removeExtension(path string) string {
	// Note: This implementation does not handle files like ".bashrc" correctly.
	if dot := strings.LastIndex(path, "."); dot != -1 {
		return path[:dot]
	}
	return path
}

// The attributes for the custom local ./bazel/gensrcs.bzl. See the .bzl file
// for attribute documentation.
type bazelGensrcsAttributes struct {
	Srcs   bazel.LabelListAttribute
	Output string
	Tools  bazel.LabelListAttribute
	Cmd    string
}

// ConvertWithBp2build converts a Soong module -> Bazel target.
func (m *Module) ConvertWithBp2build(ctx android.TopDownMutatorContext) {
	// Bazel only has the "tools" attribute.
	tools_prop := android.BazelLabelForModuleDeps(ctx, m.properties.Tools)
	tool_files_prop := android.BazelLabelForModuleSrc(ctx, m.properties.Tool_files)
	tools_prop.Append(tool_files_prop)

	tools := bazel.MakeLabelListAttribute(tools_prop)
	srcs := bazel.LabelListAttribute{}
	srcs_labels := bazel.LabelList{}
	srcs_labels = android.BazelLabelForModuleSrcExcludes(
		ctx, m.properties.Srcs, m.properties.Exclude_srcs)
	srcs = bazel.MakeLabelListAttribute(srcs_labels)

	var allReplacements bazel.LabelList
	allReplacements.Append(tools.Value)
	allReplacements.Append(bazel.FirstUniqueBazelLabelList(srcs_labels))

	// Convert the command line template.
	var cmd string
	if m.properties.Cmd != nil {
		// $(in) becomes $(SRC) in our custom gensrcs.bzl
		cmd = strings.ReplaceAll(*m.properties.Cmd, "$(in)", "$(SRC)")
		// $(out) becomes $(OUT) in our custom gensrcs.bzl
		cmd = strings.ReplaceAll(cmd, "$(out)", "$(OUT)")
		// $(gendir) becomes $(RULEDIR) in our custom gensrcs.bzl
		cmd = strings.Replace(cmd, "$(genDir)", "$(RULEDIR)", -1)

		// $(location) or $(locations) becomes the more explicit
		// $(location <default-tool-label>) in Bazel.
		if len(tools.Value.Includes) > 0 {
			cmd = strings.Replace(cmd, "$(location)",
				fmt.Sprintf("$(location %s)", tools.Value.Includes[0].Label), -1)
			cmd = strings.Replace(cmd, "$(locations)",
				fmt.Sprintf("$(locations %s)", tools.Value.Includes[0].Label), -1)
		}

		// Translate all the other $(location <name>) and $(locations <name>)
		// expansion placeholders.
		for _, l := range allReplacements.Includes {
			bpLoc := fmt.Sprintf("$(location %s)", l.OriginalModuleName)
			bpLocs := fmt.Sprintf("$(locations %s)", l.OriginalModuleName)
			bazelLoc := fmt.Sprintf("$(location %s)", l.Label)
			bazelLocs := fmt.Sprintf("$(locations %s)", l.Label)
			cmd = strings.Replace(cmd, bpLoc, bazelLoc, -1)
			cmd = strings.Replace(cmd, bpLocs, bazelLocs, -1)
		}
	}

	tags := android.ApexAvailableTags(m)

	// The Output_extension prop is not in an immediately accessible field
	// in the Module struct, so use GetProperties and cast it
	// to the known struct prop.
	var outputFileTemplate string
	for _, propIntf := range m.GetProperties() {
		if props, ok := propIntf.(*codegenProperties); ok {
			// Convert the output path template.
			outputFileTemplate = proptools.String(props.Output)
			if len(outputFileTemplate) > 0 {
				outputFileTemplate = strings.Replace(
					outputFileTemplate, "$(in)", "$(SRC:BASE)", -1)
				outputFileTemplate = strings.Replace(
					outputFileTemplate, "$(in:path/base.ext)", "$(SRC:PATH/BASE.EXT)", -1)
				outputFileTemplate = strings.Replace(
					outputFileTemplate, "$(in:path/base)", "$(SRC:PATH/BASE)", -1)
				outputFileTemplate = strings.Replace(
					outputFileTemplate, "$(in:base.ext)", "$(SRC:BASE.EXT)", -1)
				outputFileTemplate = strings.Replace(
					outputFileTemplate, "$(in:base)", "$(SRC:BASE)", -1)
			} else {
				outputFileTemplate = proptools.String(props.Prefix) + "$(SRC:BASE)" +
					proptools.String(props.Suffix)
			}
			break
		}
	}
	props := bazel.BazelTargetModuleProperties{
		Rule_class:        "gensrcs",
		Bzl_load_location: "//external/wayland-protocols/bazel:gensrcs.bzl",
	}
	attrs := &bazelGensrcsAttributes{
		Srcs:   srcs,
		Output: outputFileTemplate,
		Cmd:    cmd,
		Tools:  tools,
	}
	ctx.CreateBazelTargetModule(props, android.CommonAttributes{
		Name: m.Name(),
		Tags: tags,
	}, attrs)
}

// Defaults module.
type Defaults struct {
	android.ModuleBase
	android.DefaultsModuleBase
}

func defaultsFactory() android.Module {
	return DefaultsFactory()
}

func DefaultsFactory(props ...interface{}) android.Module {
	module := &Defaults{}

	module.AddProperties(props...)
	module.AddProperties(
		&generatorProperties{},
		&codegenProperties{},
	)

	android.InitDefaultsModule(module)

	return module
}