package main

import (
	"fmt"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"strings"
)

func main() {
	if err := run(); err != nil {
		fmt.Fprintf(os.Stderr, "build_android_apk: %v\n", err)
		os.Exit(1)
	}
}

func run() error {
	workDir, err := os.Getwd()
	if err != nil {
		return err
	}
	gogioDir, err := commandOutput("go", "list", "-m", "-f", "{{.Dir}}", "gioui.org/cmd")
	if err != nil {
		return err
	}
	tempDir, err := os.MkdirTemp("", "keepassgo-gogio-")
	if err != nil {
		return err
	}
	defer os.RemoveAll(tempDir)

	tempModule := filepath.Join(tempDir, "gioui-cmd")
	if err := copyDir(gogioDir, tempModule); err != nil {
		return err
	}
	targetFile := filepath.Join(tempModule, "gogio", "androidbuild.go")
	if err := patchAndroidBuild(targetFile); err != nil {
		return err
	}
	if err := runCommand(tempModule, "gofmt", "-w", targetFile); err != nil {
		return err
	}
	if err := refreshTempModuleDeps(tempModule); err != nil {
		return err
	}

	javaHome := os.Getenv("JAVA_HOME")
	wrappedJavaHome := javaHome
	var cleanup func()
	if major := javaMajor(javaHome); major >= 26 {
		wrappedJavaHome, cleanup, err = wrapJavaHome(javaHome)
		if err != nil {
			return err
		}
		defer cleanup()
	}

	patchedArgs := append([]string(nil), os.Args[1:]...)
	if len(patchedArgs) != 0 {
		last := patchedArgs[len(patchedArgs)-1]
		if strings.HasPrefix(last, ".") {
			patchedArgs[len(patchedArgs)-1] = filepath.Join(workDir, last)
		}
	}
	gogioFiles, err := filepath.Glob(filepath.Join(tempModule, "gogio", "*.go"))
	if err != nil {
		return err
	}
	filteredFiles := make([]string, 0, len(gogioFiles))
	for _, file := range gogioFiles {
		if strings.HasSuffix(file, "_test.go") {
			continue
		}
		filteredFiles = append(filteredFiles, file)
	}
	if len(filteredFiles) == 0 {
		return fmt.Errorf("no gogio go files found in %s", tempModule)
	}
	args := append([]string{"run"}, filteredFiles...)
	args = append(args, patchedArgs...)
	cmd := exec.Command("go", args...)
	cmd.Dir = workDir
	cmd.Env = append(os.Environ(), "JAVA_HOME="+wrappedJavaHome)
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	return cmd.Run()
}

func patchAndroidBuild(path string) error {
	data, err := os.ReadFile(path)
	if err != nil {
		return err
	}
	content := string(data)

	content = strings.Replace(content,
		"\tAppName     string\n}",
		"\tAppName             string\n\tApplicationSnippets string\n}",
		1,
	)
	content = strings.Replace(content,
		"\tif err := visitPkg(pkgs[0]); err != nil {\n\t\treturn err\n\t}\n\n\tif err := compileAndroid(tmpDir, tools, bi); err != nil {\n",
		"\tif err := visitPkg(pkgs[0]); err != nil {\n\t\treturn err\n\t}\n\tmoduleRoot := androidModuleRoot(bi.pkgDir)\n\tmoduleAndroidJars, err := filepath.Glob(filepath.Join(moduleRoot, \"android\", \"*.jar\"))\n\tif err != nil {\n\t\treturn err\n\t}\n\textraJars = append(extraJars, moduleAndroidJars...)\n\n\tif err := compileAndroid(tmpDir, tools, bi); err != nil {\n",
		1,
	)
	content = strings.Replace(content,
		"\terr = os.WriteFile(filepath.Join(v21Dir, \"themes.xml\"), []byte(themesV21), 0660)\n\tif err != nil {\n\t\treturn err\n\t}\n\tresZip := filepath.Join(tmpDir, \"resources.zip\")\n",
		"\terr = os.WriteFile(filepath.Join(v21Dir, \"themes.xml\"), []byte(themesV21), 0660)\n\tif err != nil {\n\t\treturn err\n\t}\n\tmoduleRoot := androidModuleRoot(bi.pkgDir)\n\tcustomResDir := filepath.Join(moduleRoot, \"android\", \"res\")\n\tif _, err := os.Stat(customResDir); err == nil {\n\t\tif err := copyAndroidDir(customResDir, resDir); err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n\tresZip := filepath.Join(tmpDir, \"resources.zip\")\n",
		1,
	)
	content = strings.Replace(content,
		"\t\tIconSnip:    iconSnip,\n\t\tAppName:     appName,\n\t}\n",
		"\t\tIconSnip:            iconSnip,\n\t\tAppName:             appName,\n\t\tApplicationSnippets: loadAndroidSnippet(filepath.Join(moduleRoot, \"android\", \"application_snippets.xml\")),\n\t}\n",
		1,
	)
	content = strings.Replace(content,
		"\t\t</activity>\n\t</application>\n</manifest>`)\n",
		"\t\t</activity>\n{{.ApplicationSnippets}}\n\t</application>\n</manifest>`)\n",
		1,
	)

	insertPos := strings.Index(content, "func findNDK(")
	if insertPos < 0 {
		return fmt.Errorf("findNDK not found")
	}
	helpers := `
func loadAndroidSnippet(path string) string {
	data, err := os.ReadFile(path)
	if err != nil {
		return ""
	}
	content := strings.TrimSpace(string(data))
	if content == "" {
		return ""
	}
	return "\n" + content
}

func copyAndroidDir(src, dst string) error {
	return filepath.Walk(src, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		rel, err := filepath.Rel(src, path)
		if err != nil {
			return err
		}
		target := filepath.Join(dst, rel)
		if info.IsDir() {
			return os.MkdirAll(target, 0755)
		}
		data, err := os.ReadFile(path)
		if err != nil {
			return err
		}
		return os.WriteFile(target, data, 0660)
	})
}

func androidModuleRoot(start string) string {
	dir := start
	for {
		if _, err := os.Stat(filepath.Join(dir, "go.mod")); err == nil {
			return dir
		}
		parent := filepath.Dir(dir)
		if parent == dir {
			return start
		}
		dir = parent
	}
}

`
	content = content[:insertPos] + helpers + content[insertPos:]

	return os.WriteFile(path, []byte(content), 0o644)
}

func commandOutput(name string, args ...string) (string, error) {
	cmd := exec.Command(name, args...)
	out, err := cmd.Output()
	if err != nil {
		var stderr []byte
		if exitErr, ok := err.(*exec.ExitError); ok {
			stderr = exitErr.Stderr
		}
		return "", fmt.Errorf("%s %s failed: %s%s", name, strings.Join(args, " "), out, stderr)
	}
	return strings.TrimSpace(string(out)), nil
}

func runCommand(dir, name string, args ...string) error {
	cmd := exec.Command(name, args...)
	cmd.Dir = dir
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	return cmd.Run()
}

func refreshTempModuleDeps(dir string) error {
	overrides := []string{
		"golang.org/x/image@v0.37.0",
		"golang.org/x/mod@v0.33.0",
		"golang.org/x/sync@v0.20.0",
		"golang.org/x/text@v0.35.0",
		"golang.org/x/tools@v0.42.0",
	}
	args := append([]string{"get"}, overrides...)
	return runCommand(dir, "go", args...)
}

func javaMajor(javaHome string) int {
	if strings.TrimSpace(javaHome) == "" {
		return 0
	}
	cmd := exec.Command(filepath.Join(javaHome, "bin", "java"), "-version")
	output, err := cmd.CombinedOutput()
	if err != nil {
		return 0
	}
	matches := regexp.MustCompile(`version "([0-9]+)`).FindStringSubmatch(string(output))
	if len(matches) != 2 {
		return 0
	}
	var major int
	if _, err := fmt.Sscanf(matches[1], "%d", &major); err != nil {
		return 0
	}
	return major
}

func wrapJavaHome(javaHome string) (string, func(), error) {
	tempDir, err := os.MkdirTemp("", "keepassgo-java-home-")
	if err != nil {
		return "", nil, err
	}
	binDir := filepath.Join(tempDir, "bin")
	if err := os.MkdirAll(binDir, 0o755); err != nil {
		os.RemoveAll(tempDir)
		return "", nil, err
	}
	realBin := filepath.Join(javaHome, "bin")
	if err := os.WriteFile(filepath.Join(binDir, "javac"), []byte("#!/bin/sh\nexport JAVA_TOOL_OPTIONS=-Xint\nexec "+shellQuote(filepath.Join(realBin, "javac"))+" \"$@\"\n"), 0o755); err != nil {
		os.RemoveAll(tempDir)
		return "", nil, err
	}
	for _, name := range []string{"java", "jar"} {
		if err := os.WriteFile(filepath.Join(binDir, name), []byte("#!/bin/sh\nexec "+shellQuote(filepath.Join(realBin, name))+" \"$@\"\n"), 0o755); err != nil {
			os.RemoveAll(tempDir)
			return "", nil, err
		}
	}
	return tempDir, func() { os.RemoveAll(tempDir) }, nil
}

func shellQuote(value string) string {
	return "'" + strings.ReplaceAll(value, "'", "'\\''") + "'"
}

func copyDir(src, dst string) error {
	return filepath.Walk(src, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		rel, err := filepath.Rel(src, path)
		if err != nil {
			return err
		}
		target := filepath.Join(dst, rel)
		if info.IsDir() {
			return os.MkdirAll(target, 0o755)
		}
		in, err := os.Open(path)
		if err != nil {
			return err
		}
		defer in.Close()
		out, err := os.Create(target)
		if err != nil {
			return err
		}
		defer out.Close()
		if _, err := io.Copy(out, in); err != nil {
			return err
		}
		return out.Close()
	})
}