package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"strings"
	"time"
)

func newApp() *app {
	defaultCfg := defaultConfig()
	defaultForm := formFromConfig(defaultCfg)
	settingsPath := resolveSettingsPath()

	savedForm, err := loadSettings(settingsPath)
	if err != nil {
		log.Printf("load settings failed: %v", err)
	}

	return &app{
		cfg:          defaultCfg,
		form:         mergeForm(defaultForm, savedForm),
		settingsPath: settingsPath,
		lastError:    loadSettingsErrorMessage(err),
	}
}

func (a *app) handleIndex(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path != "/" {
		http.NotFound(w, r)
		return
	}
	if r.Method != http.MethodGet {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}

	a.renderPage(w, formValues{}, "", "")
}

func (a *app) handleStart(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}

	form := formFromRequest(r)
	cfg, err := parseConfig(form)
	if err != nil {
		a.renderPage(w, form, "", err.Error())
		return
	}

	normalizedForm := formFromConfig(cfg)
	saveErr := a.persistForm(normalizedForm)

	if err := a.startWatcher(cfg); err != nil {
		a.renderPage(w, normalizedForm, "", joinMessages(err.Error(), saveErrorMessage(saveErr)))
		return
	}

	a.renderPage(w, normalizedForm, "监听任务已启动，配置已保存到本地", saveErrorMessage(saveErr))
}

func (a *app) handleStop(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}

	message := "当前没有正在运行的监听任务"
	if a.stopWatcher() {
		message = "已发送停止请求"
	}

	a.renderPage(w, formValues{}, message, "")
}

func (a *app) persistForm(form formValues) error {
	a.mu.Lock()
	a.form = form
	a.mu.Unlock()

	if err := saveSettings(a.settingsPath, form); err != nil {
		a.addLogf("save settings failed: %v", err)
		return err
	}

	a.mu.Lock()
	if strings.HasPrefix(a.lastError, "读取本地配置失败") || strings.HasPrefix(a.lastError, "配置保存失败") {
		a.lastError = ""
	}
	a.mu.Unlock()
	return nil
}

func (a *app) startWatcher(cfg config) error {
	cfg, err := validateConfig(cfg)
	if err != nil {
		return err
	}

	if cfg.archive.enabled {
		if err := ensureExistingDir(cfg.archive.sourceDir); err != nil {
			return fmt.Errorf("压缩包规则源路径错误: %w", err)
		}
		if err := ensureDir(cfg.archive.zipDir); err != nil {
			return fmt.Errorf("压缩包规则 zip 路径错误: %w", err)
		}
		if err := ensureDir(cfg.archive.unzipDir); err != nil {
			return fmt.Errorf("压缩包规则 unzip 路径错误: %w", err)
		}
	}

	if cfg.generic.enabled {
		if err := ensureExistingDir(cfg.generic.sourceDir); err != nil {
			return fmt.Errorf("普通文件规则源路径错误: %w", err)
		}
		if err := ensureDir(cfg.generic.targetDir); err != nil {
			return fmt.Errorf("普通文件规则目标路径错误: %w", err)
		}
	}

	ctx, cancel := context.WithCancel(context.Background())

	a.mu.Lock()
	if a.cancel != nil {
		a.cancel()
	}
	a.runID++
	runID := a.runID
	a.cancel = cancel
	a.running = true
	a.startedAt = time.Now()
	a.lastError = ""
	a.lastMessage = "监听任务运行中"
	a.cfg = cfg
	a.form = formFromConfig(cfg)
	a.mu.Unlock()

	if cfg.archive.enabled {
		a.addLogf("archive watcher enabled: source=%q zip=%q unzip=%q", cfg.archive.sourceDir, cfg.archive.zipDir, cfg.archive.unzipDir)
	}
	if cfg.generic.enabled {
		a.addLogf(
			"generic watcher enabled: source=%q target=%q extensions=%s dedupe=%s",
			cfg.generic.sourceDir,
			cfg.generic.targetDir,
			strings.Join(cfg.generic.extensions, ", "),
			cfg.generic.dedupeMode,
		)
	}
	a.addLogf("common settings: interval=%s stable_for=%s stable_scans=%d mode=%s recursive=%t",
		cfg.interval, cfg.stableFor, cfg.stableScans, cfg.mode, cfg.recursive)

	go a.runWatcher(ctx, runID, cfg)
	return nil
}

func (a *app) stopWatcher() bool {
	a.mu.RLock()
	cancel := a.cancel
	running := a.running
	a.mu.RUnlock()

	if cancel == nil || !running {
		return false
	}

	a.addLogf("stop requested from web UI")
	cancel()
	return true
}

func (a *app) runWatcher(ctx context.Context, runID int64, cfg config) {
	defer a.finishRun(runID)

	archiveState := make(map[string]fileState)
	genericState := make(map[string]fileState)

	runScan := func() {
		var errorsFound []string

		if cfg.archive.enabled {
			err := scanRule(
				"压缩包规则",
				cfg.archive.sourceDir,
				cfg.recursive,
				func(name string) bool {
					return strings.HasSuffix(strings.ToLower(name), tarGzSuffix)
				},
				cfg,
				archiveState,
				func(sourcePath string) (string, bool, error) {
					return processArchiveCandidate(cfg, sourcePath)
				},
				a.addLogf,
			)
			if err != nil {
				errorsFound = append(errorsFound, "压缩包规则扫描失败: "+err.Error())
			}
		}

		if cfg.generic.enabled {
			err := scanRule(
				"普通文件规则",
				cfg.generic.sourceDir,
				cfg.recursive,
				func(name string) bool {
					return matchesExtensions(name, cfg.generic.extensions)
				},
				cfg,
				genericState,
				func(sourcePath string) (string, bool, error) {
					return processGenericCandidate(cfg, sourcePath)
				},
				a.addLogf,
			)
			if err != nil {
				errorsFound = append(errorsFound, "普通文件规则扫描失败: "+err.Error())
			}
		}

		if len(errorsFound) > 0 {
			message := strings.Join(errorsFound, "；")
			a.setLastError(message)
			a.addLogf("%s", message)
			return
		}
		a.setLastError("")
	}

	runScan()

	ticker := time.NewTicker(cfg.interval)
	defer ticker.Stop()

	for {
		select {
		case <-ctx.Done():
			a.addLogf("watcher stopped")
			return
		case <-ticker.C:
			runScan()
		}
	}
}

func (a *app) finishRun(runID int64) {
	a.mu.Lock()
	defer a.mu.Unlock()

	if a.runID != runID {
		return
	}

	a.running = false
	a.cancel = nil
	a.lastMessage = "监听任务已停止"
}

func (a *app) setLastError(message string) {
	a.mu.Lock()
	defer a.mu.Unlock()
	a.lastError = message
}

func (a *app) addLogf(format string, args ...any) {
	msg := fmt.Sprintf(format, args...)
	log.Print(msg)

	line := fmt.Sprintf("%s %s", time.Now().Format("2006-01-02 15:04:05"), msg)

	a.mu.Lock()
	defer a.mu.Unlock()

	a.logs = append(a.logs, line)
	if len(a.logs) > maxLogLines {
		a.logs = a.logs[len(a.logs)-maxLogLines:]
	}
}

func (a *app) renderPage(w http.ResponseWriter, override formValues, submitMessage, submitError string) {
	page := a.snapshot()
	if hasFormInput(override) {
		page.Form = override
	}
	page.SubmitMessage = submitMessage
	page.SubmitError = submitError

	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := pageTemplate.Execute(w, page); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}
}

func (a *app) snapshot() pageData {
	a.mu.RLock()
	defer a.mu.RUnlock()

	logs := append([]string(nil), a.logs...)
	startedAt := ""
	if !a.startedAt.IsZero() {
		startedAt = a.startedAt.Format("2006-01-02 15:04:05")
	}

	return pageData{
		Running:      a.running,
		StartedAt:    startedAt,
		LastMessage:  a.lastMessage,
		LastError:    a.lastError,
		SettingsPath: a.settingsPath,
		Form:         a.form,
		Logs:         logs,
	}
}