package main

import (
	"archive/zip"
	"bufio"
	"errors"
	"fmt"
	"io"
	"log"
	"math/rand"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"sort"
	"strings"
	"time"

	tea "github.com/charmbracelet/bubbletea"
)

var initServiceNameArg string

func main() {
	commands := defaultCommands()
	args := os.Args[1:]
	if len(args) > 0 && args[0] == "--" {
		args = args[1:]
	}

	if len(args) == 0 {
		printUsage(commands)
		return
	}

	if isHelpFlag(args[0]) {
		printUsage(commands)
		return
	}

	initServiceNameArg = ""
	if args[0] == "init" && len(args) > 1 {
		initServiceNameArg = args[1]
	}

	if args[0] == "menu" {
		if err := tea.NewProgram(newModel()).Start(); err != nil {
			log.Fatal(err)
		}
		return
	}

	if err := runCommandByName(commands, args[0]); err != nil {
		log.Fatal(err)
	}
}

func defaultCommands() []command {
	return []command{
		{name: "init", description: "start a new PocketBase project", action: runInit},
		{name: "dev", description: "run the PocketBase binary locally", action: runDev},
		{name: "setup", description: "provision the remote server and install PocketBase", action: runSetup},
		{name: "deploy", description: "sync migrations/hooks/static assets (runs setup if needed)", action: runDeploy},
		{name: "logs", description: "show PocketBase logs", action: runLogs},
		{name: "secrets", description: "manage deployment secrets", action: placeholderAction("secrets")},
	}
}

type commandAction func() error

type command struct {
	name        string
	description string
	action      commandAction
}

func runCommandByName(commands []command, name string) error {
	for _, cmd := range commands {
		if cmd.name == name {
			return cmd.action()
		}
	}
	return fmt.Errorf("unknown command %q", name)
}

func printUsage(commands []command) {
	fmt.Println("Usage: pb <command> [options]")
	fmt.Println()
	fmt.Println("Options:")
	fmt.Println("  -h, --help     show this help message")
	fmt.Println()
	fmt.Println("Commands:")
	for _, cmd := range commands {
		fmt.Printf("  %-10s %s\n", cmd.name, cmd.description)
	}
	fmt.Println()
	fmt.Println("Use \"pb menu\" for an interactive helper.")
}

func isHelpFlag(arg string) bool {
	return arg == "-h" || arg == "--help"
}

func newModel() model {
	return model{commands: defaultCommands()}
}

type model struct {
	commands    []command
	cursor      int
	status      string
	running     bool
	lastCommand string
}

type commandResultMsg struct {
	name string
	err  error
}

func (m model) Init() tea.Cmd {
	return nil
}

func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
	switch msg := msg.(type) {
	case tea.KeyMsg:
		switch msg.String() {
		case "ctrl+c", "q":
			return m, tea.Quit
		case "up", "k":
			if m.running {
				return m, nil
			}
			if m.cursor > 0 {
				m.cursor--
			} else {
				m.cursor = len(m.commands) - 1
			}
			return m, nil
		case "down", "j":
			if m.running {
				return m, nil
			}
			if m.cursor < len(m.commands)-1 {
				m.cursor++
			} else {
				m.cursor = 0
			}
			return m, nil
		case "enter":
			if m.running {
				return m, nil
			}
			selected := m.commands[m.cursor]
			m.running = true
			m.lastCommand = selected.name
			m.status = fmt.Sprintf("Running %s...", selected.name)
			return m, runCommand(selected)
		}
	case commandResultMsg:
		m.running = false
		if msg.err != nil {
			m.status = fmt.Sprintf("%s failed: %v", msg.name, msg.err)
		} else {
			m.status = fmt.Sprintf("%s finished successfully", msg.name)
		}
		return m, nil
	}
	return m, nil
}

func (m model) View() string {
	var b strings.Builder
	b.WriteString("PocketBase deployment helper\n\n")
	for idx, cmd := range m.commands {
		cursor := " "
		if m.cursor == idx {
			cursor = ">"
		}
		b.WriteString(fmt.Sprintf("%s %s\n    %s\n", cursor, cmd.name, cmd.description))
	}
	b.WriteString("\n")
	if m.status != "" {
		b.WriteString(fmt.Sprintf("%s\n\n", m.status))
	}
	if m.running {
		b.WriteString("(running... press ctrl+c to abort)\n")
	}
	b.WriteString("↑/↓ to navigate, enter to run, q to quit\n")
	return b.String()
}

func runCommand(cmd command) tea.Cmd {
	return func() tea.Msg {
		return commandResultMsg{name: cmd.name, err: cmd.action()}
	}
}

func placeholderAction(name string) commandAction {
	return func() error {
		fmt.Printf("TODO: implement %s command\n", name)
		return nil
	}
}

func runInit() error {
	cwd, err := os.Getwd()
	if err != nil {
		return err
	}

	pbPath := filepath.Join(cwd, "pb.toml")
	if _, err := os.Stat(pbPath); err == nil {
		return fmt.Errorf("pb.toml already exists, aborting")
	} else if !errors.Is(err, os.ErrNotExist) {
		return err
	}

	defaultName := generateServiceName()
	serviceName, err := resolveServiceName(defaultName)
	if err != nil {
		return err
	}

	if err := writePBConfig(pbPath, serviceName); err != nil {
		return err
	}

	targetDir := filepath.Join(cwd, "bin")
	if err := os.MkdirAll(targetDir, 0o755); err != nil {
		return err
	}
	if err := os.WriteFile(filepath.Join(targetDir, ".keep"), []byte{}, 0o644); err != nil {
		return err
	}

	binaryPath := filepath.Join(targetDir, pocketbaseBinaryName(runtime.GOOS))
	if err := ensurePocketbaseBinary(defaultPocketbaseVersion, runtime.GOOS, runtime.GOARCH, binaryPath); err != nil {
		return err
	}

	if err := ensureGitignoreEntries(filepath.Join(cwd, ".gitignore"), []string{"bin/pocketbase", "pb_data", ".env", ".DS_store"}); err != nil {
		return err
	}

	fmt.Printf("Initialized PocketBase project %q\n", serviceName)
	return nil
}

func runDev() error {
	cwd, err := os.Getwd()
	if err != nil {
		return err
	}

	binaryPath := filepath.Join(cwd, "bin", pocketbaseBinaryName(runtime.GOOS))
	if err := ensurePocketbaseBinary(defaultPocketbaseVersion, runtime.GOOS, runtime.GOARCH, binaryPath); err != nil {
		return err
	}

	overrides, err := loadEnv(filepath.Join(cwd, ".env"))
	if err != nil {
		return err
	}

	cmd := exec.Command(binaryPath, "serve")
	cmd.Args = append(cmd.Args, "--dir", filepath.Join(cwd, "pb_data"))
	cmd.Dir = cwd
	cmd.Env = mergeEnv(overrides)
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	cmd.Stdin = os.Stdin

	fmt.Println("starting PocketBase development server")
	return cmd.Run()
}

const defaultPocketbaseVersion = "0.35.1"

func init() {
	rand.Seed(time.Now().UnixNano())
}

func writePBConfig(path, serviceName string) error {
	const tmpl = `[pocketbase]
version = "%s"
service_name = "%s"

[server]
ip = "127.0.0.1"
port = 8090
domain = "example.com"

`
	return os.WriteFile(path, []byte(fmt.Sprintf(tmpl, defaultPocketbaseVersion, serviceName)), 0o644)
}

func generateServiceName() string {
	adjectives := []string{"sunny", "silent", "cobalt", "rusty", "plush", "brisk", "sage", "glow"}
	nouns := []string{"harbor", "delta", "bloom", "atlas", "ripple", "ember", "lumen", "orbit"}
	adjective := adjectives[rand.Intn(len(adjectives))]
	noun := nouns[rand.Intn(len(nouns))]
	return fmt.Sprintf("%s-%s", adjective, noun)
}

func promptServiceName(defaultName string) (string, error) {
	reader := bufio.NewReader(os.Stdin)
	fmt.Printf("Service name [%s]: ", defaultName)
	input, err := reader.ReadString('\n')
	if err != nil {
		return "", err
	}
	input = strings.TrimSpace(input)
	if input == "" {
		return defaultName, nil
	}
	return input, nil
}

func resolveServiceName(defaultName string) (string, error) {
	if override := strings.TrimSpace(initServiceNameArg); override != "" {
		initServiceNameArg = ""
		return override, nil
	}
	return promptServiceName(defaultName)
}

func pocketbaseBinaryName(goos string) string {
	if goos == "windows" {
		return "pocketbase.exe"
	}
	return "pocketbase"
}

func downloadPocketbase(version, goos, goarch, dest string) error {
	url, binaryName, err := releaseAssetURL(version, goos, goarch)
	if err != nil {
		return err
	}

	resp, err := http.Get(url)
	if err != nil {
		return fmt.Errorf("failed to download %s: %w", url, err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("unexpected status %s while downloading %s", resp.Status, url)
	}

	tmpFile, err := os.CreateTemp("", "pocketbase-*.zip")
	if err != nil {
		return err
	}
	defer os.Remove(tmpFile.Name())
	defer tmpFile.Close()

	label := fmt.Sprintf("Downloading PocketBase v%s (%s/%s)", version, goos, goarch)
	if err := downloadWithProgress(tmpFile, resp.Body, resp.ContentLength, label); err != nil {
		return err
	}

	if err := extractBinary(tmpFile.Name(), binaryName, dest); err != nil {
		return err
	}

	return os.Chmod(dest, 0o755)
}

func ensurePocketbaseBinary(version, goos, goarch, dest string) error {
	if _, err := os.Stat(dest); err == nil {
		return nil
	} else if !errors.Is(err, os.ErrNotExist) {
		return err
	}

	fmt.Println("PocketBase binary missing; downloading...")
	return downloadPocketbase(version, goos, goarch, dest)
}

func downloadWithProgress(dst io.Writer, src io.Reader, total int64, label string) error {
	const chunkSize = 32 * 1024
	buf := make([]byte, chunkSize)
	var downloaded int64
	lastPercent := int64(-1)

	updateProgress := func(force bool) {
		if total > 0 {
			percent := downloaded * 100 / total
			if force || percent != lastPercent {
				fmt.Printf("\r%s %3d%%", label, percent)
				lastPercent = percent
			}
		} else {
			fmt.Printf("\r%s %s downloaded", label, formatBytes(downloaded))
		}
	}

	for {
		n, err := src.Read(buf)
		if n > 0 {
			if _, writeErr := dst.Write(buf[:n]); writeErr != nil {
				fmt.Println()
				return writeErr
			}
			downloaded += int64(n)
			updateProgress(false)
		}

		if err != nil {
			if err == io.EOF {
				break
			}
			fmt.Println()
			return err
		}
	}

	updateProgress(true)
	fmt.Println()
	return nil
}

func formatBytes(b int64) string {
	const unit = 1024
	if b < unit {
		return fmt.Sprintf("%d B", b)
	}
	div, exp := int64(unit), 0
	for n := b / unit; n >= unit; n /= unit {
		div *= unit
		exp++
	}
	return fmt.Sprintf("%.1f %cB", float64(b)/float64(div), "KMGTPE"[exp])
}

func releaseAssetURL(version, goos, goarch string) (string, string, error) {
	osName := map[string]string{
		"darwin":  "darwin",
		"linux":   "linux",
		"windows": "windows",
	}
	archName := map[string]string{
		"amd64": "amd64",
		"386":   "386",
		"arm64": "arm64",
		"arm":   "armv7",
	}

	osPart, ok := osName[goos]
	if !ok {
		return "", "", fmt.Errorf("unsupported GOOS: %s", goos)
	}
	archPart, ok := archName[goarch]
	if !ok {
		return "", "", fmt.Errorf("unsupported GOARCH: %s", goarch)
	}

	filename := fmt.Sprintf("pocketbase_%s_%s_%s.zip", version, osPart, archPart)
	url := fmt.Sprintf("https://github.com/pocketbase/pocketbase/releases/download/v%s/%s", version, filename)
	return url, pocketbaseBinaryName(goos), nil
}

func extractBinary(zipPath, binaryName, dest string) error {
	r, err := zip.OpenReader(zipPath)
	if err != nil {
		return err
	}
	defer r.Close()

	for _, f := range r.File {
		if filepath.Base(f.Name) != binaryName {
			continue
		}

		if err := os.MkdirAll(filepath.Dir(dest), 0o755); err != nil {
			return err
		}

		src, err := f.Open()
		if err != nil {
			return err
		}
		defer src.Close()

		out, err := os.OpenFile(dest, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o755)
		if err != nil {
			return err
		}
		defer out.Close()

		if _, err := io.Copy(out, src); err != nil {
			return err
		}

		return nil
	}
	return fmt.Errorf("binary %s not found in archive", binaryName)
}

func ensureGitignoreEntries(path string, entries []string) error {
	var existing = make(map[string]struct{})
	var original []byte
	if data, err := os.ReadFile(path); err == nil {
		original = data
		for _, line := range strings.Split(string(data), "\n") {
			trimmed := strings.TrimSpace(line)
			if trimmed != "" {
				existing[trimmed] = struct{}{}
			}
		}
	} else if !errors.Is(err, os.ErrNotExist) {
		return err
	}

	builder := &strings.Builder{}
	if len(original) > 0 {
		builder.Write(original)
		if !strings.HasSuffix(string(original), "\n") {
			builder.WriteByte('\n')
		}
	}

	var added bool
	for _, entry := range entries {
		if _, seen := existing[entry]; seen {
			continue
		}
		builder.WriteString(entry)
		builder.WriteByte('\n')
		added = true
	}

	if !added {
		return nil
	}

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

func loadEnv(path string) (map[string]string, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			return nil, nil
		}
		return nil, err
	}

	env := make(map[string]string)
	for _, line := range strings.Split(string(data), "\n") {
		line = strings.TrimSpace(line)
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		idx := strings.Index(line, "=")
		if idx == -1 {
			continue
		}
		key := strings.TrimSpace(line[:idx])
		value := strings.TrimSpace(line[idx+1:])
		env[key] = value
	}
	return env, nil
}

func mergeEnv(overrides map[string]string) []string {
	envMap := make(map[string]string)
	for _, kv := range os.Environ() {
		parts := strings.SplitN(kv, "=", 2)
		key := parts[0]
		value := ""
		if len(parts) > 1 {
			value = parts[1]
		}
		envMap[key] = value
	}
	for key, value := range overrides {
		envMap[key] = value
	}

	keys := make([]string, 0, len(envMap))
	for key := range envMap {
		keys = append(keys, key)
	}
	sort.Strings(keys)

	env := make([]string, 0, len(keys))
	for _, key := range keys {
		env = append(env, fmt.Sprintf("%s=%s", key, envMap[key]))
	}
	return env
}