package db

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"time"

	"git.pengzhan.dev/haopengzhan/rsspipe/internal/models"
	"github.com/google/uuid"
	_ "modernc.org/sqlite"
)

type DB struct {
	*sql.DB
}

func InitDB(dbPath string) (*DB, error) {
	dir := filepath.Dir(dbPath)
	if err := os.MkdirAll(dir, 0755); err != nil {
		return nil, fmt.Errorf("failed to create db directory: %w", err)
	}

	db, err := sql.Open("sqlite", dbPath)
	if err != nil {
		return nil, fmt.Errorf("failed to open sqlite db: %w", err)
	}

	db.SetMaxOpenConns(10)
	db.SetMaxIdleConns(5)
	db.SetConnMaxLifetime(time.Hour)

	pragmas := []string{
		"PRAGMA journal_mode = WAL;",
		"PRAGMA busy_timeout = 5000;",
		"PRAGMA synchronous = NORMAL;",
		"PRAGMA foreign_keys = ON;",
	}
	for _, p := range pragmas {
		if _, err := db.Exec(p); err != nil {
			return nil, fmt.Errorf("failed to set pragma %s: %w", p, err)
		}
	}

	database := &DB{DB: db}
	if err := database.migrate(); err != nil {
		return nil, fmt.Errorf("failed to run migrations: %w", err)
	}

	return database, nil
}

func (d *DB) migrate() error {
	schema := `
	CREATE TABLE IF NOT EXISTS users (
		id TEXT PRIMARY KEY,
		username TEXT UNIQUE NOT NULL,
		password_hash TEXT NOT NULL,
		created_at DATETIME NOT NULL,
		updated_at DATETIME NOT NULL
	);

	CREATE TABLE IF NOT EXISTS categories (
		id TEXT PRIMARY KEY,
		title TEXT NOT NULL,
		parent_id TEXT,
		sort_order INTEGER DEFAULT 0,
		created_at DATETIME NOT NULL,
		FOREIGN KEY(parent_id) REFERENCES categories(id) ON DELETE SET NULL
	);

	CREATE TABLE IF NOT EXISTS feeds (
		id TEXT PRIMARY KEY,
		title TEXT NOT NULL,
		feed_url TEXT UNIQUE NOT NULL,
		site_url TEXT,
		category_id TEXT,
		is_virtual_digest BOOLEAN DEFAULT 0,
		refresh_interval_minutes INTEGER DEFAULT 30,
		timeout_seconds INTEGER DEFAULT 10,
		etag TEXT DEFAULT '',
		last_modified TEXT DEFAULT '',
		last_fetched_at DATETIME,
		fetch_error TEXT DEFAULT '',
		created_at DATETIME NOT NULL,
		FOREIGN KEY(category_id) REFERENCES categories(id) ON DELETE SET NULL
	);

	CREATE TABLE IF NOT EXISTS feed_entries (
		id TEXT PRIMARY KEY,
		feed_id TEXT NOT NULL,
		guid TEXT NOT NULL,
		url TEXT NOT NULL,
		title TEXT NOT NULL,
		author TEXT DEFAULT '',
		content TEXT NOT NULL,
		raw_content TEXT DEFAULT '',
		published_at DATETIME NOT NULL,
		is_read BOOLEAN DEFAULT 0,
		is_starred BOOLEAN DEFAULT 0,
		share_uuid TEXT UNIQUE,
		metadata TEXT DEFAULT '{}',
		created_at DATETIME NOT NULL,
		FOREIGN KEY(feed_id) REFERENCES feeds(id) ON DELETE CASCADE,
		UNIQUE(feed_id, guid)
	);

	CREATE INDEX IF NOT EXISTS idx_entries_feed_read ON feed_entries(feed_id, is_read);
	CREATE INDEX IF NOT EXISTS idx_entries_published ON feed_entries(published_at DESC);
	CREATE INDEX IF NOT EXISTS idx_entries_is_read ON feed_entries(is_read);
	CREATE INDEX IF NOT EXISTS idx_entries_is_starred ON feed_entries(is_starred);
	CREATE INDEX IF NOT EXISTS idx_entries_share_uuid ON feed_entries(share_uuid);

	CREATE TABLE IF NOT EXISTS rules (
		id TEXT PRIMARY KEY,
		name TEXT NOT NULL,
		rule_type TEXT NOT NULL,
		is_active BOOLEAN DEFAULT 1,
		trigger_type TEXT NOT NULL,
		trigger_config TEXT DEFAULT '{}',
		conditions TEXT DEFAULT '[]',
		actions TEXT DEFAULT '[]',
		created_at DATETIME NOT NULL,
		updated_at DATETIME NOT NULL
	);
	`
	if _, err := d.Exec(schema); err != nil {
		return err
	}
	// Migration for timeout_seconds column if older DB exists
	_, _ = d.Exec("ALTER TABLE feeds ADD COLUMN timeout_seconds INTEGER DEFAULT 10")
	return nil
}

// User operations
func (d *DB) CountUsers() (int, error) {
	var count int
	err := d.QueryRow("SELECT COUNT(*) FROM users").Scan(&count)
	return count, err
}

func (d *DB) GetUserByUsername(username string) (*models.User, error) {
	var u models.User
	err := d.QueryRow(
		"SELECT id, username, password_hash, created_at, updated_at FROM users WHERE username = ?",
		username,
	).Scan(&u.ID, &u.Username, &u.PasswordHash, &u.CreatedAt, &u.UpdatedAt)
	if err != nil {
		return nil, err
	}
	return &u, nil
}

func (d *DB) CreateUser(username, passwordHash string) (*models.User, error) {
	now := time.Now().UTC()
	u := &models.User{
		ID:           uuid.New().String(),
		Username:     username,
		PasswordHash: passwordHash,
		CreatedAt:    now,
		UpdatedAt:    now,
	}
	_, err := d.Exec(
		"INSERT INTO users (id, username, password_hash, created_at, updated_at) VALUES (?, ?, ?, ?, ?)",
		u.ID, u.Username, u.PasswordHash, u.CreatedAt, u.UpdatedAt,
	)
	if err != nil {
		return nil, err
	}
	return u, nil
}

// Category operations
func (d *DB) ListCategories() ([]models.Category, error) {
	query := `
	SELECT c.id, c.title, c.parent_id, c.sort_order, c.created_at, COUNT(f.id) as feed_count
	FROM categories c
	LEFT JOIN feeds f ON f.category_id = c.id
	GROUP BY c.id
	ORDER BY c.sort_order ASC, c.title ASC
	`
	rows, err := d.Query(query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var categories []models.Category
	for rows.Next() {
		var c models.Category
		var parentID sql.NullString
		if err := rows.Scan(&c.ID, &c.Title, &parentID, &c.SortOrder, &c.CreatedAt, &c.FeedCount); err != nil {
			return nil, err
		}
		if parentID.Valid {
			p := parentID.String
			c.ParentID = &p
		}
		categories = append(categories, c)
	}
	return categories, nil
}

func (d *DB) GetCategoryByTitle(title string) (*models.Category, error) {
	var c models.Category
	var parentID sql.NullString
	err := d.QueryRow("SELECT id, title, parent_id, sort_order, created_at FROM categories WHERE title = ?", title).
		Scan(&c.ID, &c.Title, &parentID, &c.SortOrder, &c.CreatedAt)
	if err != nil {
		return nil, err
	}
	if parentID.Valid {
		p := parentID.String
		c.ParentID = &p
	}
	return &c, nil
}

func (d *DB) CreateCategory(title string, parentID *string) (*models.Category, error) {
	c := &models.Category{
		ID:        uuid.New().String(),
		Title:     title,
		ParentID:  parentID,
		SortOrder: 0,
		CreatedAt: time.Now().UTC(),
	}
	var pID interface{}
	if parentID != nil {
		pID = *parentID
	}
	_, err := d.Exec("INSERT INTO categories (id, title, parent_id, sort_order, created_at) VALUES (?, ?, ?, ?, ?)",
		c.ID, c.Title, pID, c.SortOrder, c.CreatedAt)
	if err != nil {
		return nil, err
	}
	return c, nil
}

func (d *DB) DeleteCategory(id string) error {
	_, err := d.Exec("DELETE FROM categories WHERE id = ?", id)
	return err
}

// Feed operations
func (d *DB) ListFeeds() ([]models.Feed, error) {
	query := `
	SELECT 
		f.id, f.title, f.feed_url, f.site_url, f.category_id, 
		COALESCE(c.title, '') as category_title,
		f.is_virtual_digest, f.refresh_interval_minutes, COALESCE(f.timeout_seconds, 10),
		f.etag, f.last_modified, f.last_fetched_at, f.fetch_error, f.created_at,
		COALESCE(SUM(CASE WHEN e.is_read = 0 THEN 1 ELSE 0 END), 0) as unread_count,
		COUNT(e.id) as total_count
	FROM feeds f
	LEFT JOIN categories c ON c.id = f.category_id
	LEFT JOIN feed_entries e ON e.feed_id = f.id
	GROUP BY f.id
	ORDER BY f.title ASC
	`
	rows, err := d.Query(query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var feeds []models.Feed
	for rows.Next() {
		var f models.Feed
		var catID, siteURL, etag, lastMod, fetchErr sql.NullString
		var lastFetched sql.NullTime
		if err := rows.Scan(
			&f.ID, &f.Title, &f.FeedURL, &siteURL, &catID, &f.CategoryTitle,
			&f.IsVirtualDigest, &f.RefreshIntervalMinutes, &f.TimeoutSeconds,
			&etag, &lastMod, &lastFetched, &fetchErr, &f.CreatedAt, &f.UnreadCount, &f.TotalCount,
		); err != nil {
			return nil, err
		}
		if catID.Valid {
			cid := catID.String
			f.CategoryID = &cid
		}
		if siteURL.Valid {
			f.SiteURL = siteURL.String
		}
		if etag.Valid {
			f.ETag = etag.String
		}
		if lastMod.Valid {
			f.LastModified = lastMod.String
		}
		if lastFetched.Valid {
			t := lastFetched.Time
			f.LastFetchedAt = &t
		}
		if fetchErr.Valid {
			f.FetchError = fetchErr.String
		}
		feeds = append(feeds, f)
	}
	return feeds, nil
}

func (d *DB) GetFeed(id string) (*models.Feed, error) {
	query := `
	SELECT 
		f.id, f.title, f.feed_url, f.site_url, f.category_id, 
		COALESCE(c.title, '') as category_title,
		f.is_virtual_digest, f.refresh_interval_minutes, COALESCE(f.timeout_seconds, 10),
		f.etag, f.last_modified, f.last_fetched_at, f.fetch_error, f.created_at,
		COALESCE(SUM(CASE WHEN e.is_read = 0 THEN 1 ELSE 0 END), 0) as unread_count,
		COUNT(e.id) as total_count
	FROM feeds f
	LEFT JOIN categories c ON c.id = f.category_id
	LEFT JOIN feed_entries e ON e.feed_id = f.id
	WHERE f.id = ?
	GROUP BY f.id
	`
	var f models.Feed
	var catID, siteURL, etag, lastMod, fetchErr sql.NullString
	var lastFetched sql.NullTime
	err := d.QueryRow(query, id).Scan(
		&f.ID, &f.Title, &f.FeedURL, &siteURL, &catID, &f.CategoryTitle,
		&f.IsVirtualDigest, &f.RefreshIntervalMinutes, &f.TimeoutSeconds,
		&etag, &lastMod, &lastFetched, &fetchErr, &f.CreatedAt, &f.UnreadCount, &f.TotalCount,
	)
	if err != nil {
		return nil, err
	}
	if catID.Valid {
		cid := catID.String
		f.CategoryID = &cid
	}
	if siteURL.Valid {
		f.SiteURL = siteURL.String
	}
	if etag.Valid {
		f.ETag = etag.String
	}
	if lastMod.Valid {
		f.LastModified = lastMod.String
	}
	if lastFetched.Valid {
		t := lastFetched.Time
		f.LastFetchedAt = &t
	}
	if fetchErr.Valid {
		f.FetchError = fetchErr.String
	}
	return &f, nil
}

func (d *DB) GetFeedByURL(feedURL string) (*models.Feed, error) {
	var f models.Feed
	var catID, siteURL, etag, lastMod, fetchErr sql.NullString
	var lastFetched sql.NullTime
	err := d.QueryRow(
		"SELECT id, title, feed_url, site_url, category_id, is_virtual_digest, refresh_interval_minutes, COALESCE(timeout_seconds, 10), etag, last_modified, last_fetched_at, fetch_error, created_at FROM feeds WHERE feed_url = ?",
		feedURL,
	).Scan(
		&f.ID, &f.Title, &f.FeedURL, &siteURL, &catID,
		&f.IsVirtualDigest, &f.RefreshIntervalMinutes, &f.TimeoutSeconds, &etag, &lastMod,
		&lastFetched, &fetchErr, &f.CreatedAt,
	)
	if err != nil {
		return nil, err
	}
	if catID.Valid {
		cid := catID.String
		f.CategoryID = &cid
	}
	if siteURL.Valid {
		f.SiteURL = siteURL.String
	}
	return &f, nil
}

func (d *DB) CreateFeed(title, feedURL, siteURL string, categoryID *string) (*models.Feed, error) {
	now := time.Now().UTC()
	f := &models.Feed{
		ID:                     uuid.New().String(),
		Title:                  title,
		FeedURL:                feedURL,
		SiteURL:                siteURL,
		CategoryID:             categoryID,
		RefreshIntervalMinutes: 30,
		TimeoutSeconds:         10,
		CreatedAt:              now,
	}
	var catID interface{}
	if categoryID != nil {
		catID = *categoryID
	}
	_, err := d.Exec(
		"INSERT INTO feeds (id, title, feed_url, site_url, category_id, refresh_interval_minutes, timeout_seconds, created_at) VALUES (?, ?, ?, ?, ?, ?, ?, ?)",
		f.ID, f.Title, f.FeedURL, f.SiteURL, catID, f.RefreshIntervalMinutes, f.TimeoutSeconds, f.CreatedAt,
	)
	if err != nil {
		return nil, err
	}
	return f, nil
}

func (d *DB) UpdateFeed(id string, req models.UpdateFeedRequest) error {
	feed, err := d.GetFeed(id)
	if err != nil {
		return err
	}

	title := feed.Title
	if req.Title != nil && *req.Title != "" {
		title = *req.Title
	}

	catID := feed.CategoryID
	if req.CategoryID != nil {
		if *req.CategoryID == "" {
			catID = nil
		} else {
			catID = req.CategoryID
		}
	}

	interval := feed.RefreshIntervalMinutes
	if req.RefreshIntervalMinutes != nil && *req.RefreshIntervalMinutes > 0 {
		interval = *req.RefreshIntervalMinutes
	}

	timeout := feed.TimeoutSeconds
	if req.TimeoutSeconds != nil && *req.TimeoutSeconds > 0 {
		timeout = *req.TimeoutSeconds
	}

	var cID interface{}
	if catID != nil {
		cID = *catID
	}

	_, err = d.Exec(`
		UPDATE feeds 
		SET title = ?, category_id = ?, refresh_interval_minutes = ?, timeout_seconds = ?
		WHERE id = ?
	`, title, cID, interval, timeout, id)
	return err
}

func (d *DB) UpdateFeedFetchStatus(id string, etag, lastModified, fetchErr string) error {
	now := time.Now().UTC()
	_, err := d.Exec(
		"UPDATE feeds SET etag = ?, last_modified = ?, fetch_error = ?, last_fetched_at = ? WHERE id = ?",
		etag, lastModified, fetchErr, now, id,
	)
	return err
}

func (d *DB) DeleteFeed(id string) error {
	_, err := d.Exec("DELETE FROM feeds WHERE id = ?", id)
	return err
}

// Feed Entries operations
func (d *DB) UpsertFeedEntries(feedID string, entries []models.FeedEntry) (int, error) {
	if len(entries) == 0 {
		return 0, nil
	}

	stmt, err := d.Prepare(`
		INSERT INTO feed_entries (
			id, feed_id, guid, url, title, author, content, raw_content, published_at, is_read, is_starred, metadata, created_at
		) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, 0, 0, ?, ?)
		ON CONFLICT(feed_id, guid) DO UPDATE SET
			title = excluded.title,
			content = CASE WHEN feed_entries.content = '' THEN excluded.content ELSE feed_entries.content END,
			url = excluded.url,
			author = excluded.author
	`)
	if err != nil {
		return 0, err
	}
	defer stmt.Close()

	insertedCount := 0
	for _, e := range entries {
		id := uuid.New().String()
		now := time.Now().UTC()
		pubAt := e.PublishedAt
		if pubAt.IsZero() {
			pubAt = now
		}
		metaBytes, _ := json.Marshal(e.Metadata)
		if len(metaBytes) == 0 {
			metaBytes = []byte("{}")
		}

		res, err := stmt.Exec(
			id, feedID, e.GUID, e.URL, e.Title, e.Author, e.Content, e.RawContent, pubAt, string(metaBytes), now,
		)
		if err == nil {
			if n, _ := res.RowsAffected(); n > 0 {
				insertedCount++
			}
		}
	}
	return insertedCount, nil
}

type EntryFilter struct {
	View       string // "inbox" (unread), "starred", "all"
	FeedID     string
	CategoryID string
	Search     string
	Limit      int
	Offset     int
}

func (d *DB) ListEntries(f EntryFilter) ([]models.FeedEntry, int, error) {
	where := []string{"1=1"}
	args := []interface{}{}

	if f.View == "inbox" {
		where = append(where, "e.is_read = 0")
	} else if f.View == "starred" {
		where = append(where, "e.is_starred = 1")
	}

	if f.FeedID != "" {
		where = append(where, "e.feed_id = ?")
		args = append(args, f.FeedID)
	}

	if f.CategoryID != "" {
		where = append(where, "f.category_id = ?")
		args = append(args, f.CategoryID)
	}

	if f.Search != "" {
		searchTerms := strings.Fields(f.Search)
		for _, term := range searchTerms {
			lower := strings.ToLower(term)
			if strings.HasPrefix(lower, "is:unread") {
				where = append(where, "e.is_read = 0")
			} else if strings.HasPrefix(lower, "is:read") {
				where = append(where, "e.is_read = 1")
			} else if strings.HasPrefix(lower, "is:starred") {
				where = append(where, "e.is_starred = 1")
			} else if strings.HasPrefix(lower, "feed:") {
				feedVal := strings.TrimPrefix(term, "feed:")
				where = append(where, "(f.title LIKE ? OR f.feed_url LIKE ?)")
				args = append(args, "%"+feedVal+"%", "%"+feedVal+"%")
			} else {
				where = append(where, "(e.title LIKE ? OR e.content LIKE ? OR e.author LIKE ?)")
				args = append(args, "%"+term+"%", "%"+term+"%", "%"+term+"%")
			}
		}
	}

	whereClause := strings.Join(where, " AND ")

	// Count total
	countQuery := fmt.Sprintf(`
		SELECT COUNT(*) 
		FROM feed_entries e 
		JOIN feeds f ON f.id = e.feed_id 
		WHERE %s
	`, whereClause)
	var total int
	if err := d.QueryRow(countQuery, args...).Scan(&total); err != nil {
		return nil, 0, err
	}

	limit := f.Limit
	if limit <= 0 || limit > 100 {
		limit = 50
	}
	offset := f.Offset
	if offset < 0 {
		offset = 0
	}

	query := fmt.Sprintf(`
		SELECT 
			e.id, e.feed_id, f.title as feed_title, COALESCE(f.site_url, '') as feed_site_url,
			e.guid, e.url, e.title, e.author, e.content, e.raw_content,
			e.published_at, e.is_read, e.is_starred, e.share_uuid, e.metadata, e.created_at
		FROM feed_entries e
		JOIN feeds f ON f.id = e.feed_id
		WHERE %s
		ORDER BY e.published_at DESC
		LIMIT ? OFFSET ?
	`, whereClause)

	queryArgs := append(args, limit, offset)
	rows, err := d.Query(query, queryArgs...)
	if err != nil {
		return nil, 0, err
	}
	defer rows.Close()

	var entries []models.FeedEntry
	for rows.Next() {
		var e models.FeedEntry
		var author, rawContent, metaStr sql.NullString
		var shareUUID sql.NullString
		if err := rows.Scan(
			&e.ID, &e.FeedID, &e.FeedTitle, &e.FeedSiteURL,
			&e.GUID, &e.URL, &e.Title, &author, &e.Content, &rawContent,
			&e.PublishedAt, &e.IsRead, &e.IsStarred, &shareUUID, &metaStr, &e.CreatedAt,
		); err != nil {
			return nil, 0, err
		}
		if author.Valid {
			e.Author = author.String
		}
		if rawContent.Valid {
			e.RawContent = rawContent.String
		}
		if shareUUID.Valid {
			s := shareUUID.String
			e.ShareUUID = &s
		}
		e.Metadata = make(map[string]interface{})
		if metaStr.Valid && metaStr.String != "" {
			_ = json.Unmarshal([]byte(metaStr.String), &e.Metadata)
		}
		entries = append(entries, e)
	}

	return entries, total, nil
}

func (d *DB) UpdateEntryRead(id string, isRead bool) error {
	_, err := d.Exec("UPDATE feed_entries SET is_read = ? WHERE id = ?", isRead, id)
	return err
}

func (d *DB) UpdateEntryStarred(id string, isStarred bool) error {
	_, err := d.Exec("UPDATE feed_entries SET is_starred = ? WHERE id = ?", isStarred, id)
	return err
}

func (d *DB) MarkAllRead(feedID, categoryID *string) error {
	if feedID != nil && *feedID != "" {
		_, err := d.Exec("UPDATE feed_entries SET is_read = 1 WHERE feed_id = ?", *feedID)
		return err
	}
	if categoryID != nil && *categoryID != "" {
		_, err := d.Exec(`
			UPDATE feed_entries 
			SET is_read = 1 
			WHERE feed_id IN (SELECT id FROM feeds WHERE category_id = ?)
		`, *categoryID)
		return err
	}
	_, err := d.Exec("UPDATE feed_entries SET is_read = 1")
	return err
}

func (d *DB) GetStats() (*models.Stats, error) {
	var s models.Stats
	err := d.QueryRow("SELECT COUNT(*) FROM feeds").Scan(&s.TotalFeeds)
	if err != nil {
		return nil, err
	}
	err = d.QueryRow("SELECT COUNT(*) FROM feed_entries WHERE is_read = 0").Scan(&s.TotalUnread)
	if err != nil {
		return nil, err
	}
	err = d.QueryRow("SELECT COUNT(*) FROM feed_entries WHERE is_starred = 1").Scan(&s.TotalStarred)
	if err != nil {
		return nil, err
	}
	err = d.QueryRow("SELECT COUNT(*) FROM categories").Scan(&s.TotalCategories)
	if err != nil {
		return nil, err
	}
	return &s, nil
}