package db

import (
	"context"
	"crypto/sha256"
	"database/sql"
	"encoding/hex"
	"encoding/json"
	"strings"
	"time"
)

type ArticleSummary struct {
	ID        int64     `json:"id"`
	URLHash   string    `json:"urlHash"`
	URL       string    `json:"url"`
	Events    []string  `json:"events"`
	CreatedAt time.Time `json:"createdAt"`
	ExpiresAt time.Time `json:"expiresAt"`
}

type ArticleSummaryRepository struct {
	db *PostgresDB
}

func NewArticleSummaryRepository(db *PostgresDB) *ArticleSummaryRepository {
	return &ArticleSummaryRepository{db: db}
}

func (r *ArticleSummaryRepository) hashURL(url string) string {
	normalized := strings.TrimSpace(url)
	normalized = strings.TrimSuffix(normalized, "/")
	normalized = strings.TrimPrefix(normalized, "https://")
	normalized = strings.TrimPrefix(normalized, "http://")
	normalized = strings.TrimPrefix(normalized, "www.")

	hash := sha256.Sum256([]byte(normalized))
	return hex.EncodeToString(hash[:])
}

func (r *ArticleSummaryRepository) GetByURL(ctx context.Context, url string) (*ArticleSummary, error) {
	urlHash := r.hashURL(url)

	query := `
		SELECT id, url_hash, url, events, created_at, expires_at
		FROM article_summaries 
		WHERE url_hash = $1 AND expires_at > NOW()
	`

	var a ArticleSummary
	var eventsJSON []byte

	err := r.db.db.QueryRowContext(ctx, query, urlHash).Scan(
		&a.ID, &a.URLHash, &a.URL, &eventsJSON, &a.CreatedAt, &a.ExpiresAt,
	)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}

	json.Unmarshal(eventsJSON, &a.Events)
	return &a, nil
}

func (r *ArticleSummaryRepository) Save(ctx context.Context, url string, events []string, ttl time.Duration) error {
	urlHash := r.hashURL(url)
	eventsJSON, _ := json.Marshal(events)
	expiresAt := time.Now().Add(ttl)

	query := `
		INSERT INTO article_summaries (url_hash, url, events, expires_at)
		VALUES ($1, $2, $3, $4)
		ON CONFLICT (url_hash) 
		DO UPDATE SET 
			events = EXCLUDED.events,
			expires_at = EXCLUDED.expires_at
	`

	_, err := r.db.db.ExecContext(ctx, query, urlHash, url, eventsJSON, expiresAt)
	return err
}

func (r *ArticleSummaryRepository) Delete(ctx context.Context, url string) error {
	urlHash := r.hashURL(url)
	_, err := r.db.db.ExecContext(ctx, "DELETE FROM article_summaries WHERE url_hash = $1", urlHash)
	return err
}

func (r *ArticleSummaryRepository) CleanupExpired(ctx context.Context) (int64, error) {
	result, err := r.db.db.ExecContext(ctx, "DELETE FROM article_summaries WHERE expires_at < NOW()")
	if err != nil {
		return 0, err
	}
	return result.RowsAffected()
}