# SPDX-License-Identifier: AGPL-3.0-only
# Copyright (c) 2026 sol pbc

from __future__ import annotations

from datetime import date, datetime
from pathlib import Path
from typing import Any, Callable
from urllib.parse import urlsplit

import frontmatter
from flask import (
    Blueprint,
    Response,
    current_app,
    jsonify,
    redirect,
    render_template,
    url_for,
)
from markdown import Markdown

from solstone.apps.reflections import copy as reflections_copy
from solstone.apps.reflections.dates import next_reflection_sunday
from solstone.convey.date_nav import build_date_nav_index
from solstone.convey.day_grid import build_day_grid_payload
from solstone.convey.reasons import FILE_NOT_FOUND, INVALID_MONTH
from solstone.convey.utils import DATE_RE, error_response, format_date
from solstone.think.features import require_extra
from solstone.think.utils import get_journal, get_owner_timezone, sunday_of_week

reflections_bp = Blueprint(
    "app:reflections",
    __name__,
    url_prefix="/app/reflections",
)


def _reflections_dir() -> Path:
    return Path(get_journal()) / "reflections" / "weekly"


def _plain_not_found(
    message: str = "Reflection not found",
) -> tuple[str, int, dict[str, str]]:
    return (message, 404, {"Content-Type": "text/plain; charset=utf-8"})


def _parse_day_token(day: str) -> datetime | None:
    if not DATE_RE.fullmatch(day):
        return None
    try:
        return datetime.strptime(day, "%Y%m%d")
    except ValueError:
        return None


def _canonical_week_day(day: str) -> str | None:
    day_dt = _parse_day_token(day)
    if day_dt is None:
        return None
    return sunday_of_week(day_dt, get_owner_timezone())


def _reflection_path(day: str) -> Path:
    return _reflections_dir() / f"{day}.md"


def _list_reflection_days() -> list[str]:
    reflections_dir = _reflections_dir()
    if not reflections_dir.is_dir():
        return []
    days = [
        path.stem
        for path in reflections_dir.glob("*.md")
        if path.is_file() and DATE_RE.fullmatch(path.stem)
    ]
    return sorted(days, reverse=True)


def _reflection_week_days() -> list[str]:
    days: set[str] = set()
    for day in _list_reflection_days():
        canonical_day = _canonical_week_day(day)
        if canonical_day is not None:
            days.add(canonical_day)
    return sorted(days, reverse=True)


def _format_month_name(day: str) -> str:
    return datetime.strptime(day, "%Y%m%d").strftime("%B %Y")


def _load_reflection(day: str) -> tuple[Path, str, frontmatter.Post]:
    path = _reflection_path(day)
    if not path.is_file():
        raise FileNotFoundError(day)
    raw_markdown = path.read_text(encoding="utf-8")
    return path, raw_markdown, frontmatter.loads(raw_markdown)


def _weasyprint() -> tuple[type, Callable[..., Any]]:
    require_extra("pdf-export")
    from weasyprint import HTML, default_url_fetcher

    return HTML, default_url_fetcher


def _safe_pdf_url_fetcher(url: str, *args: Any, **kwargs: Any) -> dict[str, Any]:
    _, default_url_fetcher = _weasyprint()
    scheme = urlsplit(url).scheme.lower()
    if scheme in {"http", "https"}:
        raise ValueError("Remote assets are disabled for reflection PDFs")
    return default_url_fetcher(url, *args, **kwargs)


def _render_reflection_pdf(path: Path, post: frontmatter.Post) -> bytes:
    HTML, _ = _weasyprint()
    markdown = Markdown(extensions=["extra", "sane_lists"])
    body_html = markdown.convert(post.content)
    html = render_template(
        "reflections/pdf.html",
        week_label=format_date(path.stem),
        reflection_html=body_html,
    )
    return HTML(
        string=html,
        base_url=path.parent.resolve().as_uri(),
        url_fetcher=_safe_pdf_url_fetcher,
    ).write_pdf()


def _canonical_redirect(endpoint: str, day: str) -> Response | None:
    canonical_day = _canonical_week_day(day)
    if canonical_day is None:
        return None
    if canonical_day == day:
        return None
    return redirect(url_for(endpoint, day=canonical_day), code=302)


@reflections_bp.route("/")
def index() -> Any:
    return current_app.send_static_file("shell.html")


@reflections_bp.route("/api/state")
def api_state() -> Any:
    tz = get_owner_timezone()
    today: date = datetime.now(tz).date()
    journal = Path(get_journal())
    week_days = _reflection_week_days()
    next_sunday = next_reflection_sunday(journal, today, tz)
    if next_sunday is None:
        empty_next = reflections_copy.EMPTY_NEXT_NO_DATE
        populated_next_footer = None
    else:
        empty_next = reflections_copy.EMPTY_NEXT_WITH_DATE.format(sunday=next_sunday)
        populated_next_footer = reflections_copy.POPULATED_NEXT_FOOTER.format(
            sunday=next_sunday
        )
    if week_days:
        count = len(week_days)
        month = _format_month_name(week_days[-1])
        template = (
            reflections_copy.GRID_LEDE_ONE
            if count == 1
            else reflections_copy.GRID_LEDE_OTHER
        )
        grid_lede = template.format(count=count, month=month)
    else:
        grid_lede = None

    weeks = [
        {
            "day": day,
            "label": format_date(day),
            "url": url_for("app:reflections.week_view", day=day),
        }
        for day in _list_reflection_days()
    ]
    return jsonify(
        {
            "weeks": weeks,
            "copy": {
                "subtitle": reflections_copy.SUBTITLE,
                "empty_body": reflections_copy.EMPTY_BODY,
                "empty_next": empty_next,
                "empty_until_then": reflections_copy.EMPTY_UNTIL_THEN,
                "sample_link_label": reflections_copy.SAMPLE_LINK_LABEL,
                "sample_url": url_for("app:reflections.sample"),
                "populated_framing": reflections_copy.POPULATED_FRAMING,
                "populated_sample_link": reflections_copy.POPULATED_SAMPLE_LINK,
                "populated_next_footer": populated_next_footer,
                "grid_title": reflections_copy.GRID_TITLE,
                "grid_lede": grid_lede,
                "grid_unit_one": reflections_copy.GRID_UNIT_ONE,
                "grid_unit_other": reflections_copy.GRID_UNIT_OTHER,
                "grid_unit_none": reflections_copy.GRID_UNIT_NONE,
            },
        }
    )


@reflections_bp.route("/api/index")
def api_index() -> Any:
    return jsonify(build_date_nav_index({day: 1 for day in _list_reflection_days()}))


@reflections_bp.route("/api/grid")
def api_grid() -> Any:
    tz = get_owner_timezone()
    today = datetime.now(tz).strftime("%Y%m%d")
    week_days = _reflection_week_days()
    counts = {day: 1 for day in week_days}
    coverage = {"start": week_days[-1], "end": today} if week_days else None
    return jsonify(
        build_day_grid_payload(
            counts,
            max(counts, default=None),
            coverage=coverage,
        )
    )


@reflections_bp.route("/<day>")
def week_view(day: str) -> Any:
    return current_app.send_static_file("shell.html")


@reflections_bp.route("/api/<day>")
def api_week(day: str) -> Any:
    canonical_day = _canonical_week_day(day)
    if canonical_day is None:
        return error_response(FILE_NOT_FOUND, detail="Reflection not found")

    try:
        _path, _raw_markdown, post = _load_reflection(canonical_day)
    except FileNotFoundError:
        return error_response(FILE_NOT_FOUND, detail="Reflection not found")

    return jsonify(
        {
            "day": canonical_day,
            "week_label": format_date(canonical_day),
            "markdown": post.content,
            "raw_url": url_for("app:reflections.week_raw", day=canonical_day),
            "pdf_url": url_for("app:reflections.week_pdf", day=canonical_day),
        }
    )


@reflections_bp.route("/<day>/raw")
def week_raw(day: str) -> Any:
    redirect_response = _canonical_redirect("app:reflections.week_raw", day)
    if redirect_response is not None:
        return redirect_response

    canonical_day = _canonical_week_day(day)
    if canonical_day is None:
        return _plain_not_found("Reflection not found")

    try:
        _path, raw_markdown, _post = _load_reflection(canonical_day)
    except FileNotFoundError:
        return _plain_not_found("Reflection not found")

    return (
        raw_markdown,
        200,
        {"Content-Type": "text/markdown; charset=utf-8"},
    )


@reflections_bp.route("/<day>/pdf")
def week_pdf(day: str) -> Any:
    redirect_response = _canonical_redirect("app:reflections.week_pdf", day)
    if redirect_response is not None:
        return redirect_response

    canonical_day = _canonical_week_day(day)
    if canonical_day is None:
        return _plain_not_found("Reflection not found")

    try:
        path, _raw_markdown, post = _load_reflection(canonical_day)
        pdf_bytes = _render_reflection_pdf(path, post)
    except FileNotFoundError:
        return _plain_not_found("Reflection not found")
    except ValueError as exc:
        return (str(exc), 400, {"Content-Type": "text/plain; charset=utf-8"})

    return Response(
        pdf_bytes,
        mimetype="application/pdf",
        headers={
            "Content-Disposition": (
                f'attachment; filename="reflection-{canonical_day}.pdf"'
            )
        },
    )


@reflections_bp.route("/sample")
def sample() -> Any:
    return current_app.send_static_file("shell.html")


@reflections_bp.route("/api/sample")
def api_sample() -> Any:
    post = frontmatter.loads(reflections_copy.SAMPLE_CONTENT)
    return jsonify(
        {
            "markdown": post.content,
            "raw_url": url_for("app:reflections.sample_raw"),
            "sample_banner": reflections_copy.SAMPLE_BANNER,
        }
    )


@reflections_bp.route("/sample/raw")
def sample_raw() -> Any:
    return (
        reflections_copy.SAMPLE_CONTENT,
        200,
        {"Content-Type": "text/markdown; charset=utf-8"},
    )


@reflections_bp.route("/api/stats/<month>")
def api_stats(month: str) -> Any:
    if len(month) != 6 or not month.isdigit():
        return error_response(
            INVALID_MONTH,
            detail="Invalid month format, expected YYYYMM",
        )

    stats = {day: 1 for day in _list_reflection_days() if day.startswith(month)}
    return jsonify(stats)
