// Package service — Telegram 通知 Provider。
package service

import (
	"context"
	"fmt"
	"regexp"
	"strings"
	"time"
	"unicode/utf8"
)

// TelegramProvider 通过 Telegram Bot API 发送通知。
type TelegramProvider struct{}

// Send 发送 Telegram 消息。
func (p *TelegramProvider) Send(ctx context.Context, cfg map[string]string, event NotifyEvent) error {
	botToken := cfg["bot_token"]
	chatIDs := telegramTargetChatIDs(cfg)
	parseMode := cfg["parse_mode"]
	if parseMode == "" {
		parseMode = "HTML"
	}

	if botToken == "" || len(chatIDs) == 0 {
		return fmt.Errorf("telegram: bot_token and group_chat_id/channel_chat_id are required")
	}

	text := formatTelegramMessage(event, parseMode)
	photoURL := telegramEventPhotoURL(event)

	var firstErr error
	for _, chatID := range chatIDs {
		if photoURL != "" && utf8.RuneCountInString(text) <= 1024 {
			payload := map[string]string{
				"chat_id":    chatID,
				"photo":      photoURL,
				"caption":    text,
				"parse_mode": parseMode,
			}
			if err := telegramPostJSON(ctx, cfg, "sendPhoto", payload, 15*time.Second); err == nil {
				continue
			} else if firstErr == nil {
				firstErr = err
			}
			if photo, _, err := telegramFetchRemotePhoto(ctx, cfg, photoURL, 15*time.Second); err == nil {
				fields := map[string]string{
					"chat_id":    chatID,
					"caption":    text,
					"parse_mode": parseMode,
				}
				if err := telegramPostMultipart(ctx, cfg, "sendPhoto", fields, "photo", "poster.jpg", photo, 20*time.Second); err == nil {
					continue
				} else if firstErr == nil {
					firstErr = err
				}
			} else if firstErr == nil {
				firstErr = err
			}
		}
		payload := map[string]string{
			"chat_id":    chatID,
			"text":       text,
			"parse_mode": parseMode,
		}
		if err := telegramPostJSON(ctx, cfg, "sendMessage", payload, 15*time.Second); err != nil && firstErr == nil {
			firstErr = err
		}
	}
	return firstErr
}

// ValidateConfig 验证 Telegram 配置。
func (p *TelegramProvider) ValidateConfig(cfg map[string]string) error {
	if cfg["bot_token"] == "" {
		return fmt.Errorf("telegram: bot_token is required")
	}
	if len(telegramTargetChatIDs(cfg)) == 0 {
		return fmt.Errorf("telegram: group_chat_id or channel_chat_id is required")
	}
	return nil
}

// formatTelegramMessage 格式化消息内容。
func formatTelegramMessage(event NotifyEvent, parseMode string) string {
	text := formatTelegramNotification(event)
	if parseMode == "HTML" || parseMode == "" {
		return text
	}
	result := text
	result = strings.ReplaceAll(result, "<b>", "**")
	result = strings.ReplaceAll(result, "</b>", "**")
	result = strings.ReplaceAll(result, "<code>", "`")
	result = strings.ReplaceAll(result, "</code>", "`")
	result = strings.ReplaceAll(result, "&lt;", "<")
	result = strings.ReplaceAll(result, "&gt;", ">")
	result = strings.ReplaceAll(result, "&amp;", "&")
	return result
}

func formatTelegramNotification(event NotifyEvent) string {
	if text := formatTelegramMediaNotification(event); text != "" {
		return text
	}

	var sb strings.Builder
	if tag := telegramEventTag(event); tag != "" {
		sb.WriteString(tag)
		if telegramShouldShowEventHeading(event) {
			sb.WriteString("\n")
		}
	}
	if telegramShouldShowEventHeading(event) {
		sb.WriteString(telegramEventHeading(event))
	}

	message := strings.TrimSpace(event.Message)
	if message != "" {
		if sb.Len() > 0 {
			sb.WriteString("\n\n")
		}
		sb.WriteString(formatTelegramBody(message))
	}

	fields := telegramDisplayData(event.Data)
	if len(fields) > 0 {
		if sb.Len() > 0 {
			sb.WriteString("\n")
		}
		sb.WriteString("\n")
		for _, field := range fields {
			sb.WriteString(formatTelegramField(field.key, field.value))
			sb.WriteString("\n")
		}
	}
	if links := telegramExternalLinks(event.Data); links != "" {
		sb.WriteString("\n")
		sb.WriteString(links)
	}

	return strings.TrimSpace(sb.String())
}

const (
	telegramMediaTemplateHeader    = "🐈‍⬛🐈‍⬛ MediaStationGo 更新啦 🐈‍⬛🐈‍⬛"
	telegramMediaTemplateSeparator = "--------------------------------"
)

var telegramSeasonEpisodePattern = regexp.MustCompile(`(?i)S\d{1,2}E\d{1,3}(?:[\-.~_ ]?E?\d{1,3})?`)

func formatTelegramMediaNotification(event NotifyEvent) string {
	tag := telegramMediaTag(event.Data)
	if tag == "" {
		return ""
	}

	title := telegramFirstValue(event.Data, "chinese_title", "title", "name", "media_title")
	if title == "" {
		title = telegramMessageFieldValue(event.Message, "任务", "订阅", "媒体", "资源")
	}
	originalTitle := telegramFirstValue(event.Data, "original_title", "original_name")
	originalLanguage := telegramLanguageName(telegramFirstValue(event.Data, "original_language", "language", "languages"))
	year := telegramFirstValue(event.Data, "year", "release_year")
	category := telegramMediaCategory(event.Data)
	seasonEpisode := telegramSeasonEpisodeValue(event)
	size := telegramSizeValue(event.Data)
	version := telegramVersionValue(event, seasonEpisode)
	rating := telegramFirstValue(event.Data, "rating", "score")
	genres := telegramGenresValue(telegramFirstValue(event.Data, "genres", "genre", "type"))
	overview := telegramFirstValue(event.Data, "overview", "summary", "description")
	links := telegramExternalLinks(event.Data)

	topFields := []string{}
	if title != "" {
		topFields = append(topFields, "📺 中文片名："+escapeHTML(title))
	}
	if originalTitle != "" && !strings.EqualFold(originalTitle, title) {
		topFields = append(topFields, "🧿 原始片名："+escapeHTML(originalTitle))
	}
	if originalLanguage != "" {
		topFields = append(topFields, "🌐 原始语言："+escapeHTML(originalLanguage))
	}
	if year != "" && year != "0" {
		topFields = append(topFields, "📅 发行年份："+escapeHTML(year))
	}

	mediaFields := []string{}
	if category != "" {
		mediaFields = append(mediaFields, "🐈‍⬛ 类别："+escapeHTML(category))
	}
	if seasonEpisode != "" {
		mediaFields = append(mediaFields, "🫧 季集："+escapeHTML(seasonEpisode))
	}
	if size != "" {
		mediaFields = append(mediaFields, "🔎 大小："+escapeHTML(size))
	}
	if version != "" {
		mediaFields = append(mediaFields, "📁 版本："+escapeHTML(version))
	}

	infoFields := []string{}
	if rating != "" && rating != "0" {
		infoFields = append(infoFields, "⭐️ 评分："+escapeHTML(rating))
	}
	if genres != "" {
		infoFields = append(infoFields, "💎 类型："+escapeHTML(genres))
	}
	if overview != "" {
		infoFields = append(infoFields, "🪬 简介：\n"+escapeHTML(overview))
	}

	if len(topFields) == 0 && len(mediaFields) == 0 && len(infoFields) == 0 && links == "" {
		return ""
	}

	lines := []string{telegramMediaTemplateHeader, telegramMediaTemplateSeparator, tag}
	lines = append(lines, topFields...)
	if len(mediaFields) > 0 {
		if len(topFields) > 0 {
			lines = append(lines, "")
		}
		lines = append(lines, mediaFields...)
	}
	if len(infoFields) > 0 {
		if len(topFields) > 0 || len(mediaFields) > 0 {
			lines = append(lines, "")
		}
		lines = append(lines, infoFields...)
	}
	if links != "" {
		lines = append(lines, "", telegramMediaTemplateSeparator, links)
	}
	return strings.TrimSpace(strings.Join(lines, "\n"))
}

func telegramShouldShowEventHeading(event NotifyEvent) bool {
	if telegramMediaTag(event.Data) != "" {
		return false
	}
	switch strings.TrimSpace(event.Type) {
	case EventSubscriptionHit, EventDownloadComplete:
		return false
	default:
		return true
	}
}

func telegramEventTag(event NotifyEvent) string {
	if tag := telegramMediaTag(event.Data); tag != "" {
		return tag
	}
	switch strings.TrimSpace(event.Type) {
	case EventSubscriptionHit:
		return "#订阅"
	case EventDownloadComplete:
		return "#下载完成"
	case EventScrapeFailed:
		return "#刮削失败"
	case EventSystemAlert:
		return "#系统提醒"
	case EventLibraryIngest:
		return "#入库"
	default:
		title := strings.TrimSpace(strings.TrimPrefix(event.Title, "MediaStationGo "))
		if title == "" {
			return "#MediaStationGo"
		}
		return "#" + escapeHTML(strings.ReplaceAll(title, " ", ""))
	}
}

func telegramMediaTag(data map[string]interface{}) string {
	for _, key := range []string{"media_category", "category", "media_type"} {
		value := strings.TrimSpace(telegramDataString(data, key))
		if value == "" {
			continue
		}
		lower := strings.ToLower(value)
		switch {
		case strings.Contains(value, "电影") || lower == "movie":
			return "#电影"
		case strings.Contains(value, "剧") || lower == "tv" || lower == "series" || lower == "show":
			return "#剧集"
		case strings.Contains(value, "动漫") || strings.Contains(value, "动画") || lower == "anime":
			return "#动漫"
		case strings.Contains(value, "综艺") || lower == "variety":
			return "#综艺"
		case strings.Contains(value, "纪录") || lower == "documentary":
			return "#纪录片"
		default:
			return "#" + escapeHTML(strings.ReplaceAll(value, " ", ""))
		}
	}
	return ""
}

func telegramEventHeading(event NotifyEvent) string {
	title := strings.TrimSpace(event.Title)
	title = strings.TrimSpace(strings.TrimPrefix(title, "MediaStationGo "))
	if title == "" {
		title = "MediaStationGo 通知"
	}
	icon := "🔔"
	switch strings.TrimSpace(event.Type) {
	case EventSubscriptionHit:
		icon = "🎯"
	case EventDownloadComplete:
		icon = "✅"
	case EventScrapeFailed:
		icon = "⚠️"
	case EventSystemAlert:
		icon = "🚨"
	case EventLibraryIngest:
		icon = "📚"
	}
	return fmt.Sprintf("%s <b>%s</b>", icon, escapeHTML(title))
}

func formatTelegramBody(message string) string {
	lines := strings.Split(message, "\n")
	out := make([]string, 0, len(lines))
	for _, line := range lines {
		line = strings.TrimSpace(line)
		if line == "" {
			out = append(out, "")
			continue
		}
		if strings.HasPrefix(line, "- ") {
			out = append(out, "- "+escapeHTML(strings.TrimSpace(strings.TrimPrefix(line, "- "))))
			continue
		}
		if key, ok := trimTelegramEmptyField(line); ok {
			out = append(out, fmt.Sprintf("%s <b>%s</b>：", telegramFieldIcon(telegramFieldLabel(key)), escapeHTML(telegramFieldLabel(key))))
			continue
		}
		if key, value, ok := splitTelegramField(line); ok {
			out = append(out, formatTelegramField(key, value))
			continue
		}
		out = append(out, escapeHTML(line))
	}
	return strings.TrimSpace(strings.Join(out, "\n"))
}

func trimTelegramEmptyField(line string) (string, bool) {
	line = strings.TrimSpace(line)
	for _, suffix := range []string{"：", ":"} {
		if strings.HasSuffix(line, suffix) {
			key := strings.TrimSpace(strings.TrimSuffix(line, suffix))
			if key != "" && len([]rune(key)) <= 16 {
				return key, true
			}
		}
	}
	return "", false
}

func splitTelegramField(line string) (string, string, bool) {
	idx := strings.Index(line, "：")
	sepLen := len("：")
	if idx < 0 {
		idx = strings.Index(line, ":")
		sepLen = len(":")
	}
	if idx <= 0 {
		return "", "", false
	}
	key := strings.TrimSpace(line[:idx])
	value := strings.TrimSpace(line[idx+sepLen:])
	if key == "" || value == "" || len([]rune(key)) > 16 {
		return "", "", false
	}
	return key, value, true
}

func formatTelegramField(key, value string) string {
	key = telegramFieldLabel(key)
	escapedValue := escapeHTML(strings.TrimSpace(value))
	if telegramCodeField(key) {
		escapedValue = "<code>" + escapedValue + "</code>"
	}
	return fmt.Sprintf("%s <b>%s</b>：%s", telegramFieldIcon(key), escapeHTML(key), escapedValue)
}

func telegramCodeField(key string) bool {
	key = strings.ToLower(strings.TrimSpace(key))
	return strings.Contains(key, "hash") ||
		strings.Contains(key, "路径") ||
		strings.Contains(key, "path") ||
		strings.Contains(key, "id")
}

func telegramFieldIcon(key string) string {
	switch strings.ToLower(strings.TrimSpace(key)) {
	case "中文片名", "标题", "任务", "媒体", "资源":
		return "📺"
	case "原始片名":
		return "🧿"
	case "原始语言", "语言":
		return "🌐"
	case "发行年份", "年份":
		return "📅"
	case "类别", "分类", "媒体类型":
		return "🐈‍⬛"
	case "季集", "集数":
		return "🫧"
	case "大小", "质量", "规格":
		return "🔎"
	case "版本", "保存路径":
		return "📁"
	case "评分":
		return "⭐️"
	case "类型":
		return "💎"
	case "简介":
		return "🪬"
	case "订阅":
		return "🎯"
	case "新增资源":
		return "✨"
	case "Hash":
		return "🧿"
	case "错误":
		return "⚠️"
	default:
		return "•"
	}
}