"""Battery widget: shows the frame's own last-reported battery level --
no live upstream to poll, unlike almost every other widget type. The
content is frame-level state that already exists regardless of this
widget (frame.battery_percent/battery_as_of, set by routers/device.py's
frame_battery on every device wake-on-battery report) plus routers.
common.battery_estimate_s's existing recency-weighted "how much longer"
estimate (computed there for the Device panel's own history chart) --
this widget just draws them, it doesn't fetch or compute anything new.
BatteryWidgetConfig only holds a display mode (compact: icon + percent;
detailed: also the estimate + last-report age).

No button actions -- there's nothing to advance/back/force for a number
the device itself pushes on every wake."""

from __future__ import annotations

import io
import time

from PIL import Image, ImageDraw, ImageFont
from sqlalchemy.orm import Session

from ..image_pipeline import DEFAULT_PALETTE_RGB, _quantize, draw_text, logical_render_size
from ..models import BatteryWidgetConfig, Frame, Widget
from ..routers.common import battery_estimate_s
from ._shared import placeholder_image

ACTIONS: dict = {}
ACTION_LABELS: dict[str, str] = {}

BG = (255, 255, 255)
MUTED = (110, 110, 110)

# Same thresholds/colors as manage_overlay.py's own battery glyph (not
# shared code -- that one draws onto the manage-QR overlay in a fixed
# small size, this one fills an arbitrary widget region -- but the
# "how worried should I be" color story should read the same wherever a
# battery glyph shows up on a panel). Exact panel ink RGB values, not
# arbitrary reds/yellows/greens -- a flat fill already at a palette
# color quantizes with zero dithering error once the whole composited
# canvas gets quantized, where an off-palette color would dither into a
# visible speckle at these small on-panel sizes.
_LOW = DEFAULT_PALETTE_RGB[3]  # red
_MEDIUM = DEFAULT_PALETTE_RGB[2]  # yellow
_HIGH = DEFAULT_PALETTE_RGB[5]  # green


def _fill_color(percent: int) -> tuple[int, int, int]:
    if percent <= 15:
        return _LOW
    if percent <= 40:
        return _MEDIUM
    return _HIGH


def _draw_icon(draw: ImageDraw.ImageDraw, cx: int, top: int, icon_w: int, icon_h: int, percent: int) -> None:
    stroke = max(2, icon_h // 12)
    nub_w = max(3, icon_w // 10)
    nub_h = icon_h // 2
    x0 = cx - (icon_w + nub_w) // 2
    y0 = top
    inner_x0, inner_y0 = x0 + stroke, y0 + stroke
    inner_x1, inner_y1 = x0 + icon_w - stroke, y0 + icon_h - stroke
    fill_x1 = inner_x0 + round((inner_x1 - inner_x0) * (max(0, min(100, percent)) / 100))
    if fill_x1 > inner_x0:
        draw.rectangle([inner_x0, inner_y0, fill_x1, inner_y1], fill=_fill_color(percent))
    draw.rectangle([x0, y0, x0 + icon_w, y0 + icon_h], outline=(0, 0, 0), width=stroke)
    nub_y = y0 + (icon_h - nub_h) // 2
    draw.rectangle([x0 + icon_w, nub_y, x0 + icon_w + nub_w, nub_y + nub_h], fill=(0, 0, 0))


def _format_estimate(seconds: float) -> str:
    days = seconds / 86400
    if days >= 2:
        return f"~{days:.0f}d left"
    hours = seconds / 3600
    if hours >= 20:
        return "~1d left"
    return f"~{max(1, round(hours))}h left"


def _format_age(as_of: float) -> str:
    delta = max(0.0, time.time() - as_of)
    if delta < 3600:
        return f"{max(1, round(delta / 60))}m ago"
    if delta < 86400:
        return f"{round(delta / 3600)}h ago"
    return f"{round(delta / 86400)}d ago"


def render(db: Session, frame: Frame, widget: Widget, target_w: int, target_h: int,
          is_normal_wake: bool = True) -> Image.Image:
    """is_normal_wake is unused -- see app/widgets/whiteboard.py's
    identical note; every widget type's render() shares one call
    signature regardless of which ones actually care."""
    percent = frame.battery_percent
    if percent < 0:
        return placeholder_image(target_w, target_h, ["Battery", "No reports yet"])

    cfg = db.get(BatteryWidgetConfig, widget.id)
    mode = cfg.mode if cfg else "detailed"

    img = Image.new("RGB", (target_w, target_h), BG)
    draw = ImageDraw.Draw(img)
    cx = target_w // 2

    icon_h = max(20, min(target_w, target_h) // 3)
    icon_w = int(icon_h * 1.8)
    icon_top = max(4, target_h // 8)
    _draw_icon(draw, cx, icon_top, icon_w, icon_h, percent)

    pct_font_size = max(18, min(target_w, target_h) // 3)
    pct_font = ImageFont.load_default(size=pct_font_size)
    pct_text = f"{percent}%"
    bbox = draw.textbbox((0, 0), pct_text, font=pct_font)
    pct_y = icon_top + icon_h + 10
    draw_text(img, (cx - (bbox[2] - bbox[0]) // 2, pct_y), pct_text, pct_font)

    if mode == "detailed":
        lines = []
        estimate_s = battery_estimate_s(frame, db)
        if estimate_s is not None:
            lines.append(_format_estimate(estimate_s))
        if frame.battery_as_of:
            lines.append(f"Reported {_format_age(frame.battery_as_of)}")

        small_font_size = max(11, pct_font_size // 3)
        small_font = ImageFont.load_default(size=small_font_size)
        y = pct_y + pct_font_size + 12
        for line in lines:
            if y + small_font_size > target_h - 4:
                break
            lbbox = draw.textbbox((0, 0), line, font=small_font)
            draw_text(img, (cx - (lbbox[2] - lbbox[0]) // 2, y), line, small_font, MUTED)
            y += small_font_size + 6

    return img


def render_preview_png(db: Session, frame: Frame, widget: Widget, orientation: str,
                       palette_rgb: list | None) -> bytes:
    """A normal browser-viewable PNG at full logical panel size -- same
    "dialog preview always renders at the frame's full size, not the
    widget's actual grid box" convention as text.py's render_preview_png."""
    target_w, target_h = logical_render_size(orientation)
    img = render(db, frame, widget, target_w, target_h)
    quantized = _quantize(img, palette_rgb, dither_strength=1.0)
    buf = io.BytesIO()
    quantized.convert("RGB").save(buf, format="PNG")
    return buf.getvalue()