import os
import json
from flask import Blueprint, render_template, send_file, redirect, url_for, flash

from app import db
from src.models import Issue, Article
from src.cover import generate_cover
from src.epub_builder import build_epub
import config

issues_bp = Blueprint("issues", __name__)


@issues_bp.route("/issues")
def index():
    issues = Issue.query.order_by(Issue.created_at.desc()).all()
    issue_data = []
    for issue in issues:
        article_count = len(json.loads(issue.article_ids))
        issue_data.append({
            "issue": issue,
            "article_count": article_count,
        })
    return render_template("issues.html", issues=issue_data)


@issues_bp.route("/issues/<int:issue_id>/download")
def download(issue_id):
    issue = Issue.query.get_or_404(issue_id)
    if not os.path.exists(issue.epub_path):
        flash("ePub file not found.", "error")
        return redirect(url_for("issues.index"))
    return send_file(
        issue.epub_path,
        as_attachment=True,
        download_name=os.path.basename(issue.epub_path),
    )


@issues_bp.route("/issues/<int:issue_id>/epub")
def epub_file(issue_id):
    issue = Issue.query.get_or_404(issue_id)
    if not os.path.exists(issue.epub_path):
        flash("ePub file not found.", "error")
        return redirect(url_for("issues.index"))
    return send_file(issue.epub_path, mimetype="application/epub+zip")


@issues_bp.route("/issues/<int:issue_id>/cover")
def cover_image(issue_id):
    issue = Issue.query.get_or_404(issue_id)
    if not issue.cover_path or not os.path.exists(issue.cover_path):
        flash("Cover image not found.", "error")
        return redirect(url_for("issues.index"))
    return send_file(issue.cover_path, mimetype="image/jpeg")


@issues_bp.route("/issues/<int:issue_id>/read")
def read(issue_id):
    issue = Issue.query.get_or_404(issue_id)
    if not os.path.exists(issue.epub_path):
        flash("ePub file not found.", "error")
        return redirect(url_for("issues.index"))

    article_count = len(json.loads(issue.article_ids))
    if issue.issue_type == "single_article":
        article_ids = json.loads(issue.article_ids)
        article = Article.query.get(article_ids[0]) if article_ids else None
        title = article.title if article else "Single Article"
    elif issue.issue_type == "multi_week":
        w1 = issue.week_start.isocalendar()[1]
        w2 = issue.week_end.isocalendar()[1]
        title = f"Weeks {w1}\u2013{w2}"
    else:
        title = f"Week {issue.week_start.isocalendar()[1]}"

    return render_template(
        "reader.html",
        issue=issue,
        title=title,
        article_count=article_count,
    )


@issues_bp.route("/issues/<int:issue_id>/delete", methods=["POST"])
def delete(issue_id):
    issue = Issue.query.get_or_404(issue_id)

    if issue.epub_path and os.path.exists(issue.epub_path):
        os.remove(issue.epub_path)
    if issue.cover_path and os.path.exists(issue.cover_path):
        os.remove(issue.cover_path)

    db.session.delete(issue)
    db.session.commit()

    flash("Issue deleted.")
    return redirect(url_for("issues.index"))


@issues_bp.route("/issues/<int:issue_id>/regenerate", methods=["POST"])
def regenerate(issue_id):
    issue = Issue.query.get_or_404(issue_id)
    article_ids = json.loads(issue.article_ids)

    articles_for_issue = (
        Article.query.filter(Article.id.in_(article_ids))
        .order_by(Article.pub_date.asc())
        .all()
    )
    headlines = [
        a.title for a in articles_for_issue
        if "Obituaries" not in json.loads(a.categories)
    ]
    categories_list = []
    for a in articles_for_issue:
        categories_list.extend(json.loads(a.categories))

    try:
        cover_path = generate_cover(
            issue.cover_method, config.ISSUES_DIR,
            issue.week_start, issue.week_end, headlines, categories_list
        )
        epub_path = build_epub(
            issue.week_start, issue.week_end, article_ids,
            cover_path, config.ISSUES_DIR
        )

        issue.cover_path = cover_path
        issue.epub_path = epub_path
        db.session.commit()

        flash("Issue regenerated successfully.")
    except Exception as e:
        flash(f"Regeneration failed: {e}", "error")

    return redirect(url_for("issues.index"))