// Copyright 2015 Google Inc. All rights reserved.
//
// 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 genrule

import (
	"path/filepath"

	"blueprint"
	"blueprint/pathtools"

	"android/soong/common"
)

type Config interface {
	SrcDir() string
}

var (
	pctx = blueprint.NewPackageContext("android/soong/genrule")
)

func init() {
	pctx.VariableConfigMethod("srcDir", Config.SrcDir)
}

type SourceFileGenerator interface {
	GeneratedSourceFiles() []string
}

type genSrcsProperties struct {
	// cmd: command to run on each input file.  Available variables for substitution:
	// $in: an input file
	// $out: the corresponding output file
	// $srcDir: the root directory of the source tree
	Cmd string

	// srcs: list of input files
	Srcs []string

	// output_extension: extension that will be substituted for each output file
	Output_extension string
}

func NewGenSrcs() (blueprint.Module, []interface{}) {
	module := &genSrcs{}

	return common.InitAndroidModule(module, &module.properties)
}

type genSrcs struct {
	common.AndroidModuleBase

	properties  genSrcsProperties
	outputFiles []string
}

func (g *genSrcs) GenerateAndroidBuildActions(ctx common.AndroidModuleContext) {
	rule := ctx.Rule(pctx, "genSrcs", blueprint.RuleParams{
		Command: g.properties.Cmd,
	})

	srcFiles := g.properties.Srcs
	srcFiles = pathtools.PrefixPaths(srcFiles, common.ModuleSrcDir(ctx))
	srcFiles = common.ExpandGlobs(ctx, srcFiles)

	g.outputFiles = make([]string, 0, len(srcFiles))

	for _, in := range srcFiles {
		out := pathtools.ReplaceExtension(in, g.properties.Output_extension)
		out = filepath.Join(common.ModuleGenDir(ctx), out)
		g.outputFiles = append(g.outputFiles, out)
		ctx.Build(pctx, blueprint.BuildParams{
			Rule:    rule,
			Inputs:  []string{in},
			Outputs: []string{out},
			// TODO: visit dependencies to add implicit dependencies on required tools
		})
	}
}

var _ SourceFileGenerator = (*genSrcs)(nil)

func (g *genSrcs) GeneratedSourceFiles() []string {
	return g.outputFiles
}