package services

import (
	"context"
	"fmt"
	"net"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"

	"arma3-web-server/internal/models"
)

type ProcessManager struct {
	serverfileDir string
	modsDir       string
	cfgDir        string
	profilesDir   string
	settings      *SettingsManager
	modlists      *ModlistManager
	configs       *ConfigManager
	streamer      *LogStreamer
	proc          *runningProcess
	mu            sync.RWMutex
}

type runningProcess struct {
	cmd    *exec.Cmd
	cancel context.CancelFunc
	exited chan struct{}
}

func NewProcessManager(serverfileDir, modsDir, cfgDir, profilesDir string, settings *SettingsManager, modlists *ModlistManager, configs *ConfigManager, streamer *LogStreamer) *ProcessManager {
	return &ProcessManager{
		serverfileDir: serverfileDir,
		modsDir:       modsDir,
		cfgDir:        cfgDir,
		profilesDir:   profilesDir,
		settings:      settings,
		modlists:      modlists,
		configs:       configs,
		streamer:      streamer,
	}
}

func (pm *ProcessManager) ServerfileDir() string {
	return pm.serverfileDir
}

func (pm *ProcessManager) ProfilesDir() string {
	return pm.profilesDir
}

func (pm *ProcessManager) IsRunning() bool {
	pm.mu.RLock()
	defer pm.mu.RUnlock()
	return pm.proc != nil
}

func (pm *ProcessManager) Start() error {
	pm.mu.Lock()
	if pm.proc != nil {
		pm.mu.Unlock()
		return fmt.Errorf("server already running")
	}
	pm.mu.Unlock()

	s, err := pm.settings.Load()
	if err != nil {
		return fmt.Errorf("load settings: %w", err)
	}

	s.WasRunning = true
	if err := pm.settings.Save(s); err != nil {
		return fmt.Errorf("save was_running: %w", err)
	}

	binName := "arma3server_x64"
	if s.Platform == "windows" {
		binName = "arma3server_x64.exe"
	}
	binPath := filepath.Join(pm.serverfileDir, binName)

	ctx, cancel := context.WithCancel(context.Background())
	var cmd *exec.Cmd
	if strings.Contains(s.ServerParameters, "%command%") {
		full := strings.ReplaceAll(s.ServerParameters, "%command%", binPath)
		parts := splitArgs(full)
		if len(parts) == 0 {
			cancel()
			return fmt.Errorf("empty command after %%command%% substitution")
		}
		autoArgs := pm.buildAutoArgs(s)
		cmd = exec.CommandContext(ctx, parts[0], append(parts[1:], autoArgs...)...)
	} else {
		cmd = exec.CommandContext(ctx, binPath, pm.buildArgs(s)...)
	}
	cmd.Dir = pm.serverfileDir

	stdout, err := cmd.StdoutPipe()
	if err != nil {
		cancel()
		return fmt.Errorf("stdout pipe: %w", err)
	}
	stderr, err := cmd.StderrPipe()
	if err != nil {
		cancel()
		return fmt.Errorf("stderr pipe: %w", err)
	}

	if err := cmd.Start(); err != nil {
		cancel()
		return fmt.Errorf("start: %w", err)
	}

	exited := make(chan struct{})
	pm.mu.Lock()
	pm.proc = &runningProcess{cmd: cmd, cancel: cancel, exited: exited}
	pm.mu.Unlock()

	go pm.streamer.Stream("server", stdout, "")
	go pm.streamer.Stream("server", stderr, "")

	go func() {
		cmd.Wait()
		pm.mu.Lock()
		pm.proc = nil
		pm.mu.Unlock()
		close(exited)
		pm.streamer.Broadcast("server", "[SERVER_PROCESS_EXITED]")
	}()

	return nil
}

func (pm *ProcessManager) Stop() error {
	pm.mu.Lock()
	rp := pm.proc
	pm.mu.Unlock()

	if rp == nil {
		return fmt.Errorf("server not running")
	}

	rp.cancel()
	<-rp.exited

	s, err := pm.settings.Load()
	if err == nil {
		s.WasRunning = false
		pm.settings.Save(s)
	}

	return nil
}

func (pm *ProcessManager) Restart() error {
	_ = pm.Stop()
	return pm.Start()
}

func splitArgs(raw string) []string {
	var args []string
	for _, part := range strings.Fields(raw) {
		part = strings.TrimSpace(part)
		if part != "" {
			args = append(args, part)
		}
	}
	return args
}

func (pm *ProcessManager) buildAutoArgs(s *models.ServerSettings) []string {
	var args []string

	if s.ActiveConfig != "" {
		cfgPath := filepath.Join(pm.cfgDir, s.ActiveConfig+".cfg")
		args = append(args, "-config="+cfgPath)
	}

	if s.ActiveModlist != "" {
		modPath := pm.buildModPath(s.ActiveModlist)
		if modPath != "" {
			args = append(args, modPath)
		}
	}

	if pm.profilesDir != "" && !hasArgPrefix(args, "-profiles=") {
		args = append(args, "-profiles="+pm.profilesDir)
	}

	if s.IPPort != "" && !hasArgPrefix(args, "-port=") {
		if _, portStr, err := net.SplitHostPort(s.IPPort); err == nil && portStr != "" {
			args = append(args, "-port="+portStr)
		}
	}

	return args
}

func (pm *ProcessManager) buildArgs(s *models.ServerSettings) []string {
	args := splitArgs(s.ServerParameters)
	args = append(args, pm.buildAutoArgs(s)...)
	return args
}

func hasArgPrefix(args []string, prefix string) bool {
	for _, a := range args {
		if strings.HasPrefix(a, prefix) {
			return true
		}
	}
	return false
}

const workshopAppID = "107410"

func (pm *ProcessManager) buildModPath(modlistID string) string {
	ml, err := pm.modlists.Get(modlistID)
	if err != nil {
		return ""
	}

	var parts []string
	for _, mod := range ml.Mods {
		if !mod.Enabled {
			continue
		}
		parts = append(parts, pm.resolveModPath(mod))
	}

	if len(parts) == 0 {
		return ""
	}
	return "-mod=" + strings.Join(parts, ";")
}

func (pm *ProcessManager) resolveModPath(mod models.ModEntry) string {
	if mod.Name != "" {
		p := filepath.Join(pm.modsDir, "@"+mod.Name)
		if _, err := os.Stat(p); err == nil {
			return p
		}
	}

	if mod.ID != "" {
		p := filepath.Join(pm.serverfileDir, "steamapps", "workshop", "content", workshopAppID, mod.ID)
		if _, err := os.Stat(p); err == nil {
			return p
		}
	}

	if mod.Name != "" {
		return filepath.Join(pm.modsDir, "@"+mod.Name)
	}
	return ""
}

func (pm *ProcessManager) WriteUserconfigFiles(s *models.ServerSettings) error {
	userconfigDir := filepath.Join(pm.serverfileDir, "userconfig")
	if err := os.MkdirAll(userconfigDir, 0755); err != nil {
		return err
	}

	files := map[string]string{
		"cba_settings.sqf":         s.CBASettings,
		"CfgAILevelPresets.sqf":    s.AILevelPresets,
		"CfgDifficultyPresets.sqf": s.DifficultyPresets,
	}
	for name, content := range files {
		path := filepath.Join(userconfigDir, name)
		if err := os.WriteFile(path, []byte(content), 0644); err != nil {
			return fmt.Errorf("write %s: %w", name, err)
		}
	}
	return nil
}