#!/usr/bin/env python3
import argparse
import math
import os
import re
from dataclasses import dataclass
from typing import List, Optional, Tuple

import qrcode
from PIL import Image
from reportlab.lib import colors
from reportlab.lib.pagesizes import A4
from reportlab.lib.units import mm
from reportlab.lib.utils import ImageReader
from reportlab.pdfgen import canvas
import spotipy
from spotipy.oauth2 import SpotifyClientCredentials


# ---------- Data model ----------

@dataclass
class TrackCard:
    title: str
    artists: str
    year: Optional[int]
    url: str
    qr_img: Image.Image  # PIL image


# ---------- Spotify helpers ----------

PLAYLIST_REGEXES = [
    re.compile(r"https?://open\.spotify\.com/playlist/([a-zA-Z0-9]+)"),
    re.compile(r"spotify:playlist:([a-zA-Z0-9]+)"),
]

def extract_playlist_id(url: str) -> str:
    for rx in PLAYLIST_REGEXES:
        m = rx.search(url)
        if m:
            return m.group(1)
    raise ValueError("Unsupported playlist URL. Expected open.spotify.com/playlist/<id> or spotify:playlist:<id>")

def spotify_client(client_id: str, client_secret: str) -> spotipy.Spotify:
    auth = SpotifyClientCredentials(client_id=client_id, client_secret=client_secret)
    return spotipy.Spotify(auth_manager=auth)

def fetch_tracks(sp: spotipy.Spotify, playlist_id: str, limit: Optional[int] = None) -> List[dict]:
    items = []
    offset = 0
    page_size = 100
    while True:
        batch = sp.playlist_items(
            playlist_id,
            offset=offset,
            limit=page_size,
            fields="items(track(name,artists(name),external_urls.spotify,album(release_date))),total,next",
            additional_types=["track"],
        )
        for it in batch["items"]:
            if it and it.get("track"):
                items.append(it["track"])
                if limit and len(items) >= limit:
                    return items
        if not batch.get("next"):
            break
        offset += page_size
    return items

def safe_year_from_release_date(release_date: Optional[str]) -> Optional[int]:
    if not release_date:
        return None
    try:
        # release_date may be 'yyyy', 'yyyy-mm-dd', or 'yyyy-mm'
        return int(release_date.split("-")[0])
    except Exception:
        return None


# ---------- QR code helper ----------

def make_qr_pil(url: str, box_size: int = 8, border: int = 2) -> Image.Image:
    qr = qrcode.QRCode(
        version=None,  # automatic
        error_correction=qrcode.constants.ERROR_CORRECT_M,
        box_size=box_size,
        border=border,
    )
    qr.add_data(url)
    qr.make(fit=True)
    img = qr.make_image(fill_color="black", back_color="white")
    if not isinstance(img, Image.Image):
        img = img.convert("RGB")
    return img


# ---------- Typography ----------

def wrap_text(text: str, max_width: float, font_name: str, font_size: float, canv: canvas.Canvas) -> List[str]:
    # Simple greedy line-wrapping
    words = text.split()
    lines = []
    current = ""
    for w in words:
        test = (w if not current else current + " " + w)
        if canv.stringWidth(test, font_name, font_size) <= max_width:
            current = test
        else:
            if current:
                lines.append(current)
            current = w
    if current:
        lines.append(current)
    return lines


# ---------- PDF layout ----------

PAGE_W, PAGE_H = A4
CARD_W = 63 * mm
CARD_H = 88 * mm
COLS = 3
ROWS = 3
MARGIN_LR = (210 * mm - COLS * CARD_W) / 2.0
MARGIN_TB = (297 * mm - ROWS * CARD_H) / 2.0

def grid_position(index: int) -> Tuple[int, int, int]:
    """
    Returns (page_index, col, row) for a zero-based card index.
    """
    per_page = COLS * ROWS
    page = index // per_page
    pos = index % per_page
    row = pos // COLS
    col = pos % COLS
    return page, col, row

def card_origin(col: int, row: int) -> Tuple[float, float]:
    x = MARGIN_LR + col * CARD_W
    y = PAGE_H - MARGIN_TB - (row + 1) * CARD_H
    return x, y

def draw_cut_border(c: canvas.Canvas, x: float, y: float, w: float, h: float):
    c.setLineWidth(0.3)
    c.setStrokeColor(colors.lightgrey)
    c.rect(x, y, w, h, stroke=1, fill=0)
    c.setStrokeColor(colors.black)
    c.setLineWidth(1.0)

def draw_card_front(c: canvas.Canvas, x: float, y: float, card: TrackCard, qr_size_mm: float, show_year_on_front: bool):
    draw_cut_border(c, x, y, CARD_W, CARD_H)
    pad = 4 * mm
    qr_size = qr_size_mm * mm
    qr_x = x + (CARD_W - qr_size) / 2.0
    qr_y = y + CARD_H - pad - qr_size
    c.drawImage(ImageReader(card.qr_img), qr_x, qr_y, qr_size, qr_size, preserveAspectRatio=True, mask='auto')

    # Title and artist
    text_w = CARD_W - 2 * pad
    c.setFillColor(colors.black)
    # Title
    c.setFont("Helvetica-Bold", 10)
    title_lines = wrap_text(card.title, text_w, "Helvetica-Bold", 10, c)
    ty = qr_y - 4 * mm
    for line in title_lines[:3]:
        # c.drawCentredString(x + CARD_W / 2.0, ty, line)
        ty -= 4.5 * mm
    # Artist(s)
    c.setFont("Helvetica", 9)
    artists = card.artists
    artist_lines = wrap_text(artists, text_w, "Helvetica", 9, c)
    for line in artist_lines[:2]:
        # c.drawCentredString(x + CARD_W / 2.0, ty, line)
        ty -= 4.2 * mm

    # Optional year on front (small, bottom-right)
    if show_year_on_front and card.year:
        c.setFont("Helvetica", 8)
        c.setFillColor(colors.darkgrey)
        c.drawRightString(x + CARD_W - pad, y + pad, str(card.year))

def draw_card_back(c: canvas.Canvas, x: float, y: float, card: TrackCard):
    draw_cut_border(c, x, y, CARD_W, CARD_H)
    pad = 6 * mm
    c.setFillColor(colors.black)
    # Year in the centre
    if card.year:
        c.setFont("Helvetica-Bold", 28)
        c.drawCentredString(x + CARD_W / 2.0, y + CARD_H / 2.0 + 4 * mm, str(card.year))
    # Title and artist small at bottom
    c.setFont("Helvetica", 8)
    label = f"{card.title} — {card.artists}"
    text_w = CARD_W - 2 * pad
    lines = wrap_text(label, text_w, "Helvetica", 8, c)
    line_height = 9.5
    base_y = y + pad + (len(lines) - 1) * line_height
    for i, line in enumerate(lines[:3]):
        c.drawCentredString(x + CARD_W / 2.0, base_y - i * line_height, line)

def build_cards(tracks: List[dict], qr_size_mm: float) -> List[TrackCard]:
    cards: List[TrackCard] = []
    for t in tracks:
        title = (t.get("name") or "").strip()
        artists = ", ".join([a["name"] for a in (t.get("artists") or [])])
        year = safe_year_from_release_date(t.get("album", {}).get("release_date"))
        url = (t.get("external_urls") or {}).get("spotify") or ""
        if not url:
            continue
        qr_img = make_qr_pil(url, box_size=8, border=2)
        cards.append(TrackCard(title=title, artists=artists, year=year, url=url, qr_img=qr_img))
    return cards

def paginate_draw(c: canvas.Canvas, cards: List[TrackCard], draw_fn):
    per_page = COLS * ROWS
    total_pages = math.ceil(len(cards) / per_page) or 1
    for page in range(total_pages):
        start = page * per_page
        end = min(start + per_page, len(cards))
        for i in range(start, end):
            _, col, row = grid_position(i - start)
            x, y = card_origin(col, row)
            draw_fn(c, x, y, cards[i])
        if page < total_pages - 1 or end == len(cards):
            c.showPage()

def generate_pdfs(cards: List[TrackCard], out_dir: str, show_year_on_front: bool, qr_size_mm: float):
    os.makedirs(out_dir, exist_ok=True)
    fronts_path = os.path.join(out_dir, "fronts.pdf")
    backs_path = os.path.join(out_dir, "backs.pdf")

    cf = canvas.Canvas(fronts_path, pagesize=A4)
    def draw_front(c, x, y, card):
        draw_card_front(c, x, y, card, qr_size_mm=qr_size_mm, show_year_on_front=show_year_on_front)
    paginate_draw(cf, cards, draw_front)
    cf.save()

    cb = canvas.Canvas(backs_path, pagesize=A4)
    def draw_back(c, x, y, card):
        draw_card_back(c, x, y, card)
    paginate_draw(cb, cards, draw_back)
    cb.save()

def generate_pdf_interleaved(cards: List[TrackCard], out_dir: str, show_year_on_front: bool, qr_size_mm: float):
    """
    Produce one PDF: odd pages = fronts, even pages = backs, for each 3x3 page of cards.
    """
    os.makedirs(out_dir, exist_ok=True)
    out_path = os.path.join(out_dir, "cards.pdf")
    c = canvas.Canvas(out_path, pagesize=A4)
    per_page = COLS * ROWS

    def draw_front_page(page_cards: List[TrackCard]):
        for i, card in enumerate(page_cards):
            col = i % COLS
            row = i // COLS
            x, y = card_origin(col, row)
            draw_card_front(c, x, y, card, qr_size_mm=qr_size_mm, show_year_on_front=show_year_on_front)

    def draw_back_page(page_cards: List[TrackCard]):
        for i, card in enumerate(page_cards):
            col = i % COLS
            row = i // COLS
            # Straight same-order backs; add mirroring later if needed.
            x, y = card_origin(col, row)
            draw_card_back(c, x, y, card)

    for start in range(0, len(cards), per_page):
        page_cards = cards[start:start + per_page]
        draw_front_page(page_cards)
        c.showPage()
        draw_back_page(page_cards)
        c.showPage()

    c.save()
    print(f"Generated interleaved PDF: {os.path.abspath(out_path)}")

def main():
    parser = argparse.ArgumentParser(description="Generate DIN A4 Hitster-style cards from a Spotify playlist.")
    parser.add_argument("--playlist", required=True, help="Spotify playlist URL (public).")
    parser.add_argument("--client-id", required=True, help="Spotify CLIENT_ID.")
    parser.add_argument("--client-secret", required=True, help="Spotify CLIENT_SECRET.")
    parser.add_argument("--out", default="output_cards", help="Output directory for PDFs.")
    parser.add_argument("--max-cards", type=int, default=54, help="Maximum number of tracks/cards to include.")
    parser.add_argument("--qr-size-mm", type=float, default=35.0, help="QR code size on card in millimetres.")
    parser.add_argument("--year-on-front", action="store_true", help="Also print the year small on the front.")
    parser.add_argument("--one-pdf", action="store_true", help="Generate a single interleaved PDF (front page then matching back page).")
    args = parser.parse_args()

    playlist_id = extract_playlist_id(args.playlist)
    sp = spotify_client(args.client_id, args.client_secret)
    raw_tracks = fetch_tracks(sp, playlist_id, limit=args.max_cards)
    if not raw_tracks:
        raise SystemExit("No tracks fetched. Ensure the playlist is public and contains tracks.")
    cards = build_cards(raw_tracks, qr_size_mm=args.qr_size_mm)
    if not cards:
        raise SystemExit("No valid cards could be built from the playlist.")

    if args.one_pdf:
        generate_pdf_interleaved(cards, args.out, show_year_on_front=args.year_on_front, qr_size_mm=args.qr_size_mm)
    else:
        generate_pdfs(cards, args.out, show_year_on_front=args.year_on_front, qr_size_mm=args.qr_size_mm)

    print("Done.")

if __name__ == "__main__":
    main()