package client

import (
	"context"
	_ "embed"
	"fmt"
	"io"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
)

const (
	serviceLabel = "com.kotikot.lodge"
	systemdUnit  = "lodge.service"
	hookName     = "post-checkout"
)

//go:embed skill.md
var skill []byte

var skillDirs = []string{".claude/skills/lodge", ".agents/skills/lodge"}

func launchdPlist(binary, logFile string) string {
	return fmt.Sprintf(`<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>Label</key><string>%s</string>
	<key>ProgramArguments</key><array><string>%s</string><string>daemon</string></array>
	<key>RunAtLoad</key><true/>
	<key>KeepAlive</key><true/>
	<key>ProcessType</key><string>Background</string>
	<key>StandardErrorPath</key><string>%s</string>
</dict>
</plist>
`, serviceLabel, binary, logFile)
}

func systemdService(binary string) string {
	return fmt.Sprintf(`[Unit]
Description=lodge sync daemon

[Service]
ExecStart=%s daemon
Restart=always
RestartSec=5

[Install]
WantedBy=default.target
`, binary)
}

func command(name string, args ...string) error {
	out, err := exec.Command(name, args...).CombinedOutput()
	if err != nil {
		return fmt.Errorf("%s %s: %w: %s", name, strings.Join(args, " "), err, strings.TrimSpace(string(out)))
	}
	return nil
}

func launchdTarget() string {
	return "gui/" + strconv.Itoa(os.Getuid())
}

func plistPath(home string) string {
	return filepath.Join(home, "Library", "LaunchAgents", serviceLabel+".plist")
}

func unitPath(home string) string {
	return filepath.Join(home, ".config", "systemd", "user", systemdUnit)
}

func (c *Client) templateDir() string {
	return filepath.Join(c.DataDir, "git-template")
}

func (c *Client) Install() error {
	binary, err := os.Executable()
	if err != nil {
		return err
	}
	home, err := os.UserHomeDir()
	if err != nil {
		return err
	}
	if err := c.installHook(binary); err != nil {
		return err
	}
	for _, dir := range skillDirs {
		if err := writeFile(filepath.Join(home, dir, "SKILL.md"), skill, 0o644); err != nil {
			return err
		}
	}
	return startService(home, binary, filepath.Join(c.DataDir, "daemon.log"))
}

func (c *Client) installHook(binary string) error {
	template, _ := exec.Command("git", "config", "--global", "--get", "init.templateDir").Output()
	dir := strings.TrimSpace(string(template))
	if dir == "" {
		dir = c.templateDir()
		if err := command("git", "config", "--global", "init.templateDir", dir); err != nil {
			return err
		}
	}
	if home, err := os.UserHomeDir(); err == nil && strings.HasPrefix(dir, "~/") {
		dir = filepath.Join(home, dir[2:])
	}
	hook := filepath.Join(dir, "hooks", hookName)
	if existing, err := os.ReadFile(hook); err == nil && !strings.Contains(string(existing), "lodge hook") {
		fmt.Fprintf(os.Stderr, "lodge: %s already exists, add this line to it yourself: %q hook\n", hook, binary)
		return nil
	}
	script := fmt.Sprintf("#!/bin/sh\n[ -x %q ] && %q hook\nexit 0\n", binary, binary)
	return writeFile(hook, []byte(script), 0o755)
}

func startService(home, binary, logFile string) error {
	if runtime.GOOS == "darwin" {
		plist := plistPath(home)
		if err := writeFile(plist, []byte(launchdPlist(binary, logFile)), 0o644); err != nil {
			return err
		}
		_ = command("launchctl", "bootout", launchdTarget()+"/"+serviceLabel)
		return command("launchctl", "bootstrap", launchdTarget(), plist)
	}
	if err := writeFile(unitPath(home), []byte(systemdService(binary)), 0o644); err != nil {
		return err
	}
	_ = command("loginctl", "enable-linger")
	if err := command("systemctl", "--user", "daemon-reload"); err != nil {
		return err
	}
	return command("systemctl", "--user", "enable", "--now", systemdUnit)
}

func restartService() error {
	if runtime.GOOS == "darwin" {
		return command("launchctl", "kickstart", "-k", launchdTarget()+"/"+serviceLabel)
	}
	return command("systemctl", "--user", "restart", systemdUnit)
}

func (c *Client) Uninstall() error {
	home, err := os.UserHomeDir()
	if err != nil {
		return err
	}
	if runtime.GOOS == "darwin" {
		_ = command("launchctl", "bootout", launchdTarget()+"/"+serviceLabel)
		_ = os.Remove(plistPath(home))
	} else {
		_ = command("systemctl", "--user", "disable", "--now", systemdUnit)
		_ = os.Remove(unitPath(home))
	}
	template, _ := exec.Command("git", "config", "--global", "--get", "init.templateDir").Output()
	if strings.TrimSpace(string(template)) == c.templateDir() {
		_ = command("git", "config", "--global", "--unset", "init.templateDir")
	}
	for _, dir := range skillDirs {
		_ = os.RemoveAll(filepath.Join(home, dir))
	}
	return os.RemoveAll(c.templateDir())
}

func (c *Client) Update(ctx context.Context) (bool, error) {
	binary, err := os.Executable()
	if err != nil {
		return false, err
	}
	current, err := os.ReadFile(binary)
	if err != nil {
		return false, err
	}
	res, err := c.request(ctx, http.MethodGet, fmt.Sprintf("/dl/lodge-%s-%s", runtime.GOOS, runtime.GOARCH), nil)
	if err != nil {
		return false, err
	}
	defer res.Body.Close()
	latest, err := io.ReadAll(res.Body)
	if err != nil {
		return false, err
	}
	if hashOf(latest) == hashOf(current) {
		return false, nil
	}
	if err := writeFile(binary, latest, 0o755); err != nil {
		return false, err
	}
	return true, restartService()
}