package main

import (
	"database/sql"
	"encoding/xml"
	"fmt"
	"io"
	"log"
	"net/http"
	"strconv"
	"strings"
	"time"

	_ "github.com/ncruces/go-sqlite3/driver"
	_ "github.com/ncruces/go-sqlite3/embed"
)

// RSS structures
type RSS struct {
	XMLName xml.Name `xml:"rss"`
	Channel Channel  `xml:"channel"`
}

type Channel struct {
	Title string `xml:"title"`
	Items []Item `xml:"item"`
}

type Item struct {
	Title     string    `xml:"title"`
	Link      string    `xml:"link"`
	Category  string    `xml:"category"`
	Enclosure Enclosure `xml:"enclosure"`
}

type Enclosure struct {
	URL  string `xml:"url,attr"`
	Type string `xml:"type,attr"`
}

// Internal structures
type YearWeek struct {
	Year int
	Week int
}

type TitleAuthor struct {
	Title  string
	Author string
}

func parseYearWeek(date string) (YearWeek, error) {
	parts := strings.Split(date, "/")
	if len(parts) != 2 {
		return YearWeek{}, fmt.Errorf("expected 'YYYY/WW', got '%s'", date)
	}

	year, err := strconv.Atoi(parts[0])
	if err != nil {
		return YearWeek{}, fmt.Errorf("invalid year for date '%s': %w", date, err)
	}

	week, err := strconv.Atoi(parts[1])
	if err != nil {
		return YearWeek{}, fmt.Errorf("invalid week for date '%s': %w", date, err)
	}

	return YearWeek{Year: year, Week: week}, nil
}

func parseTitle(title string) (TitleAuthor, error) {
	parts := strings.Split(title, " - ")
	if len(parts) < 3 {
		return TitleAuthor{}, fmt.Errorf("expected 'Week - Author - Title', got '%s'", title)
	}

	return TitleAuthor{Title: strings.Join(parts[2:], " - "), Author: parts[1]}, nil
}

// For some tracks, like https://weeklybeats.com/keff/music/evil-los-man, the WB RSS feed returns invalid XML bytes. Scrub these.
func filterInvalidXMLBytes(data []byte) []byte {
	writePos := 0
	for _, b := range data {
		if isValidXMLByte(b) {
			data[writePos] = b
			writePos++
		}
	}
	return data[:writePos]
}

func isValidXMLByte(b byte) bool {
	// Valid XML 1.0 characters for single-byte range
	return b == 0x09 || b == 0x0A || b == 0x0D || b >= 0x20
}

func main() {
	fmt.Println("Program started")
	// Create SQLite database
	db, err := sql.Open("sqlite3", "weeklybeats.db")
	if err != nil {
		log.Fatal("Failed to open database:", err)
	}
	defer db.Close()

	// Create table
	createTable := `
	CREATE TABLE IF NOT EXISTS tracks (
		id INTEGER PRIMARY KEY AUTOINCREMENT,
		title TEXT NOT NULL,
		link TEXT NOT NULL,
		author TEXT,
		week INTEGER,
		year INTEGER,
		url TEXT,
		UNIQUE(author, week, year)
	);`

	_, err = db.Exec(createTable)
	if err != nil {
		log.Fatal("Failed to create table:", err)
	}

	fmt.Println("Starting to scrape Weekly Beats RSS feed...")

	// Prepare insert statement
	insertStmt, err := db.Prepare(`
		INSERT OR IGNORE INTO tracks (title, link, author, week, year, url) 
		VALUES (?, ?, ?, ?, ?, ?)
	`)
	if err != nil {
		log.Fatal("Failed to prepare insert statement:", err)
	}
	defer insertStmt.Close()

	year := 2012
	totalItems := 0
	for year <= 2024 {
		page := 1

		for {
			fmt.Printf("Fetching page %d for year %d...\n", page, year)

			// Construct URL with page parameter
			url := fmt.Sprintf("https://weeklybeats.com/music/rss?limit=1000&year=%d&page=%d", year, page)

			// Fetch RSS feed
			resp, err := http.Get(url)
			if err != nil {
				log.Printf("Failed to fetch page %d: %v", page, err)
				break
			}

			if resp.StatusCode != 200 {
				fmt.Printf("Received status %d for page %d, stopping\n", resp.StatusCode, page)
				resp.Body.Close()
				break
			}

			body, err := io.ReadAll(resp.Body)
			resp.Body.Close()

			if err != nil {
				log.Printf("Failed to read response body for page %d: %v", page, err)
				break
			}

			cleanedBody := filterInvalidXMLBytes(body)

			// Parse XML
			var rss RSS
			err = xml.Unmarshal(cleanedBody, &rss)
			if err != nil {
				log.Printf("Failed to parse XML for page %d: %v", page, err)
				break
			}

			// Check if we got any items
			if len(rss.Channel.Items) == 0 {
				fmt.Printf("No items found on page %d, stopping\n", page)
				break
			}

			fmt.Printf("Found %d items on page %d\n", len(rss.Channel.Items), page)

			// Insert items into database
			pageItems := 0
			for _, item := range rss.Channel.Items {
				titleAuthor, err := parseTitle(item.Title)
				if err != nil {
					log.Printf("Failed to parse title for item '%s': %v", item.Title, err)
					continue
				}

				yearWeek, err := parseYearWeek(item.Category)
				if err != nil {
					log.Printf("Failed to parse date for item '%s': %v", item.Title, err)
					continue
				}

				_, err = insertStmt.Exec(titleAuthor.Title, item.Link, titleAuthor.Author, yearWeek.Week, yearWeek.Year, item.Enclosure.URL)
				if err != nil {
					log.Printf("Failed to insert item '%s': %v", item.Title, err)
					continue
				}
				pageItems++
			}

			fmt.Printf("Inserted %d new items from page %d\n", pageItems, page)
			totalItems += pageItems

			// Be respectful to the server
			time.Sleep(500 * time.Millisecond)

			page++

			// Safety check to prevent infinite loops
			if page > 1000 {
				fmt.Println("Reached maximum page limit (1000), stopping")
				break
			}
		}

		year += 2
	}

	// Print summary
	fmt.Printf("\nScraping complete! Total items processed: %d\n", totalItems)

	// Query and display some statistics
	var count int
	err = db.QueryRow("SELECT COUNT(*) FROM tracks").Scan(&count)
	if err != nil {
		log.Printf("Failed to count records: %v", err)
	} else {
		fmt.Printf("Total records in database: %d\n", count)
	}

	// Show sample of data
	fmt.Println("\nSample of stored data:")
	rows, err := db.Query("SELECT title, author, link FROM tracks LIMIT 5")
	if err != nil {
		log.Printf("Failed to query sample data: %v", err)
		return
	}
	defer rows.Close()

	for rows.Next() {
		var title, author, link string
		err := rows.Scan(&title, &author, &link)
		if err != nil {
			log.Printf("Failed to scan row: %v", err)
			continue
		}
		fmt.Printf("- %s by %s (%s)\n", title, author, link)
	}
}