#!/usr/bin/env python3

"""
Teletext TUI for api.teletext.ch
"""

import argparse
import base64
import curses
import textwrap
import time
from dataclasses import dataclass
from typing import List, Optional, Tuple

import requests

API_BASE = "https://api.teletext.ch"
CHANNELS_DEFAULT = ["srf1", "srfzwei", "srfinfo"]

# ───────── Models ─────────


@dataclass
class Subpage:
    subpageNumber: int
    contentText: str
    ep1Info: Optional[dict] = None


@dataclass
class PageData:
    channel: str
    pageNumber: int
    nextPage: Optional[int]
    subpages: List[Subpage]
    previousPage: Optional[int] = None


# ───────── Fetch ─────────


def fetch_page(channel: str, page: int, timeout: float = 6.0) -> PageData:
    """Fetch a Teletext page JSON from the API."""
    url = f"{API_BASE}/channels/{channel}/pages/{page}"
    r = requests.get(url, timeout=timeout, headers={"Accept": "application/json"})
    r.raise_for_status()

    j = r.json()
    subs: List[Subpage] = [
        Subpage(
            subpageNumber=sp.get("subpageNumber", 0),
            contentText=sp.get("contentText") or "",
            ep1Info=sp.get("ep1Info"),
        )
        for sp in j.get("subpages", []) or []
    ]

    if not subs:
        subs = [Subpage(0, "", None)]

    return PageData(
        channel=j.get("channel", channel),
        pageNumber=j.get("pageNumber", page),
        nextPage=j.get("nextPage"),
        subpages=subs,
        previousPage=j.get("previousPage"),
    )


# ───────── Teletext decode  ─────────

GERMAN_NATIONAL_MAP = {
    0x5B: "Ä",
    0x5C: "Ö",
    0x5D: "Ü",
    0x7B: "ä",
    0x7C: "ö",
    0x7D: "ü",
    0x7E: "ß",
}


def alpha_char(b: int) -> str:
    """Map teletext character codes to Unicode."""
    return GERMAN_NATIONAL_MAP.get(b, chr(b))


def ep1_rows_text_only(ep1_info: dict) -> List[List[Tuple[str, int, int, bool]]]:
    """Decode EP1-format data into rows of (text, fg, bg, bold) segments."""
    ep1 = ep1_info.get("data", {}).get("ep1Format", {})
    header_b = base64.b64decode(ep1.get("header", "") or b"")
    content_b = base64.b64decode(ep1.get("content", "") or b"")

    def render_row(bs: bytes) -> List[Tuple[str, int, int, bool]]:
        alpha = True
        fg, bg = 7, -1
        double = False
        segs: List[Tuple[str, int, int, bool]] = []
        buf: List[str] = []

        def flush():
            nonlocal buf
            if buf:
                segs.append(("".join(buf), fg, bg, double))
                buf = []

        i = 0
        while i < len(bs):
            b = bs[i]
            if b < 0x20:
                if 0x00 <= b <= 0x07:
                    flush()
                    fg = b
                    alpha = True
                elif b == 0x0C:
                    flush()
                    double = False
                elif b == 0x0D:
                    flush()
                    double = True
                elif b == 0x0F:
                    flush()
                    alpha = False
                elif 0x10 <= b <= 0x17:
                    flush()
                    fg = b - 0x10
                    alpha = False
                elif b == 0x1C:
                    flush()
                    bg = -1
                elif b == 0x1D:
                    flush()
                    bg = fg
                elif b == 0x1F:
                    alpha = True
                i += 1
                continue

            buf.append(alpha_char(b) if alpha else " ")
            i += 1

        flush()
        total = sum(len(s) for s, _, _, _ in segs)
        if total < 40:
            segs.append((" " * (40 - total), fg, bg, double))
        elif total > 40:
            over = total - 40
            s, cf, cb, db = segs[-1]
            segs[-1] = (s[:-over], cf, cb, db)
        return segs

    rows = []
    if len(header_b) >= 40:
        rows.append(render_row(header_b[:40]))
    for i in range(0, len(content_b), 40):
        chunk = content_b[i : i + 40]
        if not chunk:
            break
        rows.append(render_row(chunk))

    def is_blank(row):
        return "".join(s for s, _, _, _ in row).strip() == ""

    while rows and is_blank(rows[-1]):
        rows.pop()
    return rows


# ───────── UI helpers ─────────


def wrap_plain(text: str, width: int) -> List[str]:
    """Wrap plain text into lines without breaking whitespace."""
    out = []
    for line in text.splitlines():
        out.extend(
            textwrap.wrap(
                line, width=width, replace_whitespace=False, drop_whitespace=False
            )
            or [""]
        )
    return out


def draw_bar(stdscr, msg, row, width, pair=0):
    """Draw a single-line colored bar."""
    msg = (msg[: width - 1]).ljust(width - 1)
    if pair:
        stdscr.attron(curses.color_pair(pair))
    stdscr.addstr(row, 0, msg)
    if pair:
        stdscr.attroff(curses.color_pair(pair))


# ───────── TUI ─────────


def run_tui(initial_channel: str, initial_page: int, channels: List[str]):
    def main(stdscr):
        curses.curs_set(0)
        stdscr.nodelay(True)
        stdscr.timeout(100)
        curses.start_color()
        curses.use_default_colors()

        curses.init_pair(1, curses.COLOR_BLACK, curses.COLOR_CYAN)  # header
        curses.init_pair(2, curses.COLOR_BLACK, curses.COLOR_WHITE)  # footer
        curses.init_pair(3, curses.COLOR_RED, -1)  # error

        pair_base = 20
        pair_idx = {}
        palette = [
            curses.COLOR_BLACK,
            curses.COLOR_RED,
            curses.COLOR_GREEN,
            curses.COLOR_YELLOW,
            curses.COLOR_BLUE,
            curses.COLOR_MAGENTA,
            curses.COLOR_CYAN,
            curses.COLOR_WHITE,
        ]

        def pair_for(fg: int, bg: int) -> int:
            key = (fg, bg)
            if key in pair_idx:
                return pair_idx[key]
            pid = pair_base + len(pair_idx)
            curses.init_pair(
                pid,
                palette[max(0, min(7, fg))],
                -1 if bg == -1 else palette[max(0, min(7, bg))],
            )
            pair_idx[key] = pid
            return pid

        channel_idx = next(
            (i for i, c in enumerate(channels) if c == initial_channel), 0
        )
        channel = channels[channel_idx]
        page = initial_page
        sub_idx = 0
        input_buf = ""
        status = "Ready."
        last_status_at = time.time()

        try:
            pd = fetch_page(channel, page)
            status = f"Loaded {channel}:{page}"
        except Exception as e:
            pd = PageData(channel, page, None, [Subpage(0, f"Error: {e}", None)])
            status = f"Error loading {channel}:{page} – {e}"

        while True:
            stdscr.erase()
            h, w = stdscr.getmaxyx()
            if h < 8 or w < 42:
                stdscr.addstr(0, 0, "Please resize terminal (>= 42x8).")
                stdscr.refresh()
                time.sleep(0.1)
                continue

            header = (
                f" Teletext {pd.channel}  Page {pd.pageNumber}  "
                f"Sub {min(sub_idx + 1, len(pd.subpages))}/{max(1, len(pd.subpages))}  "
                "[q] quit  [0..9 Enter] goto  [h/l] prev/next  [c] channel  [r] reload"
            )
            draw_bar(stdscr, header, 0, w, 1)

            body_h, body_w = h - 3, w
            sp = pd.subpages[min(sub_idx, len(pd.subpages) - 1)]

            if sp.contentText:
                for i, line in enumerate(wrap_plain(sp.contentText, body_w)[:body_h]):
                    stdscr.addnstr(1 + i, 0, line, body_w - 1)
            elif sp.ep1Info:
                rows = ep1_rows_text_only(sp.ep1Info)
                r_i = 0
                for row in rows:
                    if r_i >= body_h:
                        break
                    col = 0
                    is_double = any(b for _, _, _, b in row)
                    for txt, fg, bg, bold in row:
                        if col >= body_w - 1:
                            break
                        chunk = txt[: max(0, body_w - 1 - col)]
                        attrs = curses.color_pair(pair_for(fg, bg)) | (
                            curses.A_BOLD if bold else 0
                        )
                        stdscr.addstr(1 + r_i, col, chunk, attrs)
                        col += len(chunk)
                    r_i += 1
                    if is_double and r_i < body_h:
                        stdscr.addstr(1 + r_i, 0, " " * min(40, body_w - 1))
                        r_i += 1
            else:
                stdscr.addstr(1, 0, "(empty)")

            draw_bar(stdscr, f"Go to page: {input_buf}", h - 2, w, 2)
            if time.time() - last_status_at > 3:
                status = ""
            draw_bar(
                stdscr, status, h - 1, w, 0 if not status.startswith("Error") else 3
            )

            stdscr.refresh()
            ch = stdscr.getch()
            if ch == -1:
                continue

            if ch in (ord("q"), ord("Q")):
                break
            if ch in (ord("h"), curses.KEY_LEFT):
                if sub_idx > 0:
                    sub_idx -= 1
                else:
                    if isinstance(pd.previousPage, int):
                        page = pd.previousPage
                        sub_idx = 0
                        try:
                            pd = fetch_page(channel, page)
                            status = f"Loaded {channel}:{page}"
                        except Exception as e:
                            status = f"Error loading {channel}:{page} – {e}"
                        last_status_at = time.time()
                continue
            if ch in (ord("l"), curses.KEY_RIGHT):
                if sub_idx + 1 < len(pd.subpages):
                    sub_idx += 1
                else:
                    if isinstance(pd.nextPage, int):
                        page = pd.nextPage
                        sub_idx = 0
                        try:
                            pd = fetch_page(channel, page)
                            status = f"Loaded {channel}:{page}"
                        except Exception as e:
                            status = f"Error loading {channel}:{page} – {e}"
                        last_status_at = time.time()
                continue
            if ch in (ord("c"), ord("C")):
                channel_idx = (channel_idx + 1) % len(channels)
                channel = channels[channel_idx]
                sub_idx = 0
                try:
                    pd = fetch_page(channel, page)
                    status = f"Channel {channel}"
                except Exception as e:
                    status = f"Error loading {channel}:{page} – {e}"
                last_status_at = time.time()
                continue
            if ch in (ord("r"), ord("R")):
                try:
                    pd = fetch_page(channel, page)
                    sub_idx = min(sub_idx, len(pd.subpages) - 1)
                    status = f"Reloaded {channel}:{page}"
                except Exception as e:
                    status = f"Error reloading {channel}:{page} – {e}"
                last_status_at = time.time()
                continue
            if ch in (curses.KEY_BACKSPACE, 127, 8):
                input_buf = input_buf[:-1]
                continue
            if ch in (curses.KEY_ENTER, 10, 13):
                if input_buf.strip().isdigit():
                    page = int(input_buf)
                    sub_idx = 0
                    try:
                        pd = fetch_page(channel, page)
                        status = f"Loaded {channel}:{page}"
                    except Exception as e:
                        status = f"Error loading {channel}:{page} – {e}"
                    last_status_at = time.time()
                input_buf = ""
                continue
            if 48 <= ch <= 57 and len(input_buf) < 4:
                input_buf += chr(ch)

    curses.wrapper(main)


# ───────── CLI ─────────


def parse_args():
    ap = argparse.ArgumentParser(description="Teletext TUI for api.teletext.ch")
    ap.add_argument("--channel", default="srf1")
    ap.add_argument("--page", type=int, default=100)
    return ap.parse_args()


def main():
    args = parse_args()
    run_tui(args.channel, args.page, CHANNELS_DEFAULT)


if __name__ == "__main__":
    main()