// Copyright 2019 The Ebiten Authors
//
// 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 main

import (
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
)

const gomobileHash = "aaac322e2105241d1ac9a25b03d4e916ac6e42c6"

func runCommand(command string, args []string, env []string) error {
	if buildX || buildN {
		for _, e := range env {
			fmt.Printf("%s ", e)
		}
		fmt.Print(command)
		for _, arg := range args {
			fmt.Printf(" %s", arg)
		}
		fmt.Println()
	}

	if buildN {
		return nil
	}

	cmd := exec.Command(command, args...)
	if len(env) > 0 {
		cmd.Env = append(os.Environ(), env...)
	}
	if out, err := cmd.CombinedOutput(); err != nil {
		return fmt.Errorf("%s %v failed: %v\n%v", command, args, string(out), err)
	}
	return nil
}

func removeAll(path string) error {
	if buildX || buildN {
		fmt.Printf("rm -rf %s\n", path)
	}
	if buildN {
		return nil
	}
	return os.RemoveAll(path)
}

func runGo(args ...string) error {
	// TODO: Remove this after Ebitengine drops the support of Go 1.15 and older.
	// GO111MODULE is on by default as of Go 1.16.
	env := []string{
		"GO111MODULE=on",
	}
	return runCommand("go", args, env)
}

// exe adds the .exe extension to the given filename.
// Without .exe, the executable won't be found by exec.LookPath on Windows (#1096).
func exe(filename string) string {
	if runtime.GOOS == "windows" {
		return filename + ".exe"
	}
	return filename
}

func prepareGomobileCommands() (string, error) {
	tmp, err := ioutil.TempDir("", "ebitenmobile-")
	if err != nil {
		return "", err
	}

	newpath := filepath.Join(tmp, "bin")
	if path := os.Getenv("PATH"); path != "" {
		newpath += string(filepath.ListSeparator) + path
	}
	if buildX || buildN {
		fmt.Printf("PATH=%s\n", newpath)
	}
	if !buildN {
		if err := os.Setenv("PATH", newpath); err != nil {
			return tmp, err
		}
	}

	pwd, err := os.Getwd()
	if err != nil {
		return tmp, err
	}

	// cd
	if buildX {
		fmt.Printf("cd %s\n", tmp)
	}
	if err := os.Chdir(tmp); err != nil {
		return tmp, err
	}
	defer func() {
		_ = os.Chdir(pwd)
	}()

	const (
		modname   = "ebitenmobiletemporary"
		buildtags = "//go:build tools" +
			"\n// +build tools"
	)
	if err := runGo("mod", "init", modname); err != nil {
		return tmp, err
	}
	if err := ioutil.WriteFile("tools.go", []byte(fmt.Sprintf(`%s

package %s

import (
	_ "golang.org/x/mobile/cmd/gobind"
	_ "golang.org/x/mobile/cmd/gomobile"
)
`, buildtags, modname)), 0644); err != nil {
		return tmp, err
	}

	// To record gomobile to go.sum for Go 1.16 and later, go-get gomobile instaed of golang.org/x/mobile (#1487).
	// This also records gobind as gomobile depends on gobind indirectly.
	// Using `...` doesn't work on Windows since mobile/internal/mobileinit cannot be compiled on Windows w/o Cgo (#1493).
	if err := runGo("get", "golang.org/x/mobile/cmd/gomobile@"+gomobileHash); err != nil {
		return tmp, err
	}
	if localgm := os.Getenv("EBITENMOBILE_GOMOBILE"); localgm != "" {
		if !filepath.IsAbs(localgm) {
			localgm = filepath.Join(pwd, localgm)
		}
		if err := runGo("mod", "edit", "-replace=golang.org/x/mobile="+localgm); err != nil {
			return tmp, err
		}
	}
	if err := runGo("mod", "tidy"); err != nil {
		return tmp, err
	}
	if err := runGo("build", "-o", exe(filepath.Join("bin", "gomobile")), "golang.org/x/mobile/cmd/gomobile"); err != nil {
		return tmp, err
	}
	if err := runGo("build", "-o", exe(filepath.Join("bin", "gobind-original")), "golang.org/x/mobile/cmd/gobind"); err != nil {
		return tmp, err
	}

	if err := os.Mkdir("src", 0755); err != nil {
		return tmp, err
	}
	if err := ioutil.WriteFile(filepath.Join("src", "gobind.go"), gobindsrc, 0644); err != nil {
		return tmp, err
	}

	if err := runGo("build", "-o", exe(filepath.Join("bin", "gobind")), "-tags", "ebitenmobilegobind", filepath.Join("src", "gobind.go")); err != nil {
		return tmp, err
	}

	if err := runCommand("gomobile", []string{"init"}, nil); err != nil {
		return tmp, err
	}

	return tmp, nil
}