"""本地模板渲染（替代 Web 端 canvas 渲染，离线可用）。
渲染产物为 400x300 RGB 图，红字用纯红 (255,0,0)，经 image_pipeline 三色量化上屏。
模板集与 Web 端对齐：schedule/businesscard/memo/course/qrcode/custom（moban.js）。
"""
from __future__ import annotations

import datetime

from PIL import Image, ImageDraw, ImageFont

W, H = 400, 300
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
RED = (255, 0, 0)

_FONT_CANDIDATES = [
    "/usr/share/fonts/truetype/wqy/wqy-zenhei.ttc",
    "/usr/share/fonts/truetype/noto/NotoSansCJK-Regular.ttc",
]

_cache: dict[int, ImageFont.FreeTypeFont] = {}


def _font(size: int) -> ImageFont.FreeTypeFont:
    if size not in _cache:
        for path in _FONT_CANDIDATES:
            try:
                _cache[size] = ImageFont.truetype(path, size)
                break
            except OSError:
                continue
        else:
            _cache[size] = ImageFont.load_default()
    return _cache[size]


def _canvas() -> tuple[Image.Image, ImageDraw.ImageDraw]:
    img = Image.new("RGB", (W, H), WHITE)
    return img, ImageDraw.Draw(img)


def _wrap_cjk(text: str, max_units: float) -> list[str]:
    """按显示宽度断行：中文=1 单位，其他=0.5（与 moban.js 自定义文本一致）。"""
    lines, cur, width = [], "", 0.0
    for ch in text:
        u = 1.0 if ord(ch) > 0x2E7F else 0.5
        if ch == "\n" or width + u > max_units:
            lines.append(cur)
            cur, width = "", 0.0
            if ch == "\n":
                continue
        cur += ch
        width += u
    lines.append(cur)
    return lines


def _draw_colored(draw: ImageDraw.ImageDraw, xy, text: str, size: int):
    """绘制含 【…】 红字段落的单行文本。返回结束 x。"""
    x, y = xy
    segs, cur, red = [], "", False
    for ch in text:
        if ch == "【":
            segs.append((cur, red)); cur, red = "", True
        elif ch == "】":
            segs.append((cur, red)); cur, red = "", False
        else:
            cur += ch
    segs.append((cur, red))
    for seg, is_red in segs:
        if not seg:
            continue
        draw.text((x, y), seg, font=_font(size), fill=RED if is_red else BLACK)
        x += draw.textlength(seg, font=_font(size))
    return x


def render_schedule(p: dict) -> Image.Image:
    """日程：{"date": "2026-07-24"(可省), "items": [["09:00","晨会【重要】"],...]}"""
    img, d = _canvas()
    date = p.get("date") or datetime.date.today().isoformat()
    d.rectangle([0, 0, W, 46], fill=BLACK)
    d.text((16, 10), f"日程 {date}", font=_font(24), fill=WHITE)
    y = 58
    for time_s, event in p.get("items", [])[:8]:
        d.text((16, y), time_s, font=_font(20), fill=BLACK)
        _draw_colored(d, (110, y), event, 20)
        d.line([(16, y + 30), (W - 16, y + 30)], fill=BLACK, width=1)
        y += 30
    return img


def render_businesscard(p: dict) -> Image.Image:
    """名片：{"name","title","company","phone","email"}"""
    img, d = _canvas()
    d.rectangle([0, 0, W, H], outline=BLACK, width=3)
    d.text((24, 30), p.get("name", ""), font=_font(40), fill=BLACK)
    d.text((24, 86), p.get("title", ""), font=_font(20), fill=RED)
    d.text((24, 116), p.get("company", ""), font=_font(20), fill=BLACK)
    d.line([(24, 150), (W - 24, 150)], fill=BLACK, width=2)
    y = 164
    for label, key in (("电话", "phone"), ("邮箱", "email"), ("地址", "addr")):
        if p.get(key):
            d.text((24, y), f"{label}：{p[key]}", font=_font(18), fill=BLACK)
            y += 28
    return img


def render_memo(p: dict) -> Image.Image:
    """备忘录：{"title": "...", "lines": ["...", ...]}"""
    img, d = _canvas()
    d.rectangle([0, 0, W, 44], fill=BLACK)
    d.text((16, 8), p.get("title", "备忘录"), font=_font(24), fill=WHITE)
    y = 56
    for line in p.get("lines", [])[:9]:
        d.ellipse([16, y + 8, 24, y + 16], fill=BLACK)
        _draw_colored(d, (32, y), line, 18)
        y += 27
    return img


def render_course(p: dict) -> Image.Image:
    """课程表：{"days": ["周一",...](≤7), "periods": 4(2–9),
    "grid": [["数学","语文",...], ...]  # grid[period][day]"""
    days = p.get("days") or ["周一", "周二", "周三", "周四", "周五"]
    periods = int(p.get("periods", 4))
    grid = p.get("grid", [])
    img, d = _canvas()
    cols = len(days) + 1
    cw, rh = W // cols, H // (periods + 1)
    for i in range(cols + 1):
        d.line([(i * cw, 0), (i * cw, H)], fill=BLACK)
    for j in range(periods + 2):
        d.line([(0, j * rh), (W, j * rh)], fill=BLACK)
    for c, day in enumerate(days):
        d.text((c * cw + cw // 2, rh // 2), day, font=_font(16),
               fill=BLACK, anchor="mm")
    for r in range(periods):
        d.text((cw // 2, (r + 1) * rh + rh // 2), f"{r + 1}", font=_font(16),
               fill=BLACK, anchor="mm")
        for c in range(len(days)):
            name = grid[r][c] if r < len(grid) and c < len(grid[r]) else ""
            if name:
                d.text(((c + 1) * cw + cw // 2, (r + 1) * rh + rh // 2),
                       name, font=_font(14), fill=BLACK, anchor="mm")
    return img


def render_qrcode(p: dict) -> Image.Image:
    """二维码：{"content": "...", "caption": "..."}（纠错级 M，与 Web 端一致）"""
    import qrcode
    qr = qrcode.QRCode(error_correction=qrcode.constants.ERROR_CORRECT_M, box_size=8, border=2)
    qr.add_data(p.get("content", ""))
    qr.make(fit=True)
    qimg = qr.make_image(fill_color="black", back_color="white").convert("RGB")
    side = min(qimg.width, 240)
    qimg = qimg.resize((side, side), Image.NEAREST)
    img, d = _canvas()
    img.paste(qimg, ((W - side) // 2, (H - side) // 2 - 14))
    caption = p.get("caption", "")
    if caption:
        d.text((W // 2, H - 34), caption, font=_font(20), fill=BLACK, anchor="mm")
    return img


def render_custom(p: dict) -> Image.Image:
    """自定义文本：{"text": "支持【红字】与换行", "size": 24(可选)}"""
    text = p.get("text", "")
    size = int(p.get("size", 24))
    img, d = _canvas()
    y = 10
    for line in _wrap_cjk(text, max_units=(W - 20) / size):
        _draw_colored(d, (10, y), line, size)
        y += int(size * 1.35)
        if y > H - size:
            break
    return img


RENDERERS = {
    "schedule": render_schedule,
    "businesscard": render_businesscard,
    "memo": render_memo,
    "course": render_course,
    "qrcode": render_qrcode,
    "custom": render_custom,
}


def render_template(name: str, payload: dict) -> Image.Image:
    try:
        return RENDERERS[name](payload)
    except KeyError:
        raise ValueError(f"未知模板 {name!r}，可选：{sorted(RENDERERS)}") from None