/**
 * Draws the screen payload as an 800x480 SVG.
 *
 * This module draws and nothing else. Every string it places has already been
 * computed and translated by the view model, so there is no business logic to
 * disagree about — which is also why its output can be snapshotted as text
 * rather than compared as pixels.
 *
 * e-ink discipline: no greys, no shadows, no gradients, no hairlines.
 * Hierarchy comes from size, weight and solid inversion.
 */

import satori from 'satori';

import type { ScreenPayload, ScreenWeekDay } from './contract';
import { loadScreenFonts } from './fonts';
import { h, type ElementNode } from './h';
import { LOGO_HEIGHT, LOGO_WIDTH, loadLogoDataUri } from './logo';
import {
  BANNER_HEIGHT,
  BLACK,
  HEADER_HEIGHT,
  PADDING,
  RULE,
  SANS,
  SCREEN_HEIGHT,
  SCREEN_WIDTH,
  SERIF,
  WEEK_HEIGHT,
  WHITE,
} from './layout';

export function screenTree(payload: ScreenPayload, logo: string | null = null): ElementNode {
  return h(
    'div',
    {
      style: {
        display: 'flex',
        flexDirection: 'column',
        width: SCREEN_WIDTH,
        height: SCREEN_HEIGHT,
        backgroundColor: WHITE,
        color: BLACK,
        fontFamily: SANS,
      },
    },
    header(payload, logo),
    main(payload),
    weekStrip(payload.week),
    banner(payload),
  );
}

function header(payload: ScreenPayload, logo: string | null): ElementNode {
  return h(
    'div',
    {
      style: {
        display: 'flex',
        alignItems: 'center',
        justifyContent: 'space-between',
        height: HEADER_HEIGHT,
        paddingLeft: PADDING,
        paddingRight: PADDING,
        borderBottom: `${RULE}px solid ${BLACK}`,
      },
    },
    logo
      ? h('img', {
          src: logo,
          width: LOGO_WIDTH,
          height: LOGO_HEIGHT,
          style: { display: 'flex' },
        })
      : h(
          'div',
          { style: { display: 'flex', fontFamily: SERIF, fontSize: 34, letterSpacing: 6 } },
          payload.shop_name,
        ),
    h('div', { style: { display: 'flex', fontSize: 22 } }, payload.today.date_fr),
  );
}

function main(payload: ScreenPayload): ElementNode {
  const { today } = payload;
  return h(
    'div',
    {
      style: {
        display: 'flex',
        flexDirection: 'column',
        flexGrow: 1,
        justifyContent: 'center',
        paddingLeft: PADDING,
        paddingRight: PADDING,
      },
    },
    h(
      'div',
      { style: { display: 'flex', fontSize: 92, fontWeight: 700, lineHeight: 1 } },
      today.status_fr,
    ),
    today.hours_text
      ? h(
          'div',
          { style: { display: 'flex', fontSize: 36, fontWeight: 600, marginTop: 10 } },
          today.hours_text,
        )
      : null,
    nextChangeLine(payload),
  );
}

function nextChangeLine(payload: ScreenPayload): ElementNode | null {
  const { next_change_fr: fr, next_change_en: en } = payload.today;
  if (!fr && !en) {
    return null;
  }
  return h(
    'div',
    { style: { display: 'flex', alignItems: 'baseline', marginTop: 12 } },
    fr ? h('div', { style: { display: 'flex', fontSize: 24 } }, fr) : null,
    fr && en ? h('div', { style: { display: 'flex', fontSize: 24, paddingLeft: 10, paddingRight: 10 } }, '·') : null,
    en ? h('div', { style: { display: 'flex', fontSize: 20 } }, en) : null,
  );
}

function weekStrip(week: ScreenWeekDay[]): ElementNode {
  return h(
    'div',
    {
      style: {
        display: 'flex',
        height: WEEK_HEIGHT,
        borderTop: `${RULE}px solid ${BLACK}`,
      },
    },
    ...week.map((day) => weekColumn(day)),
  );
}

function weekColumn(day: ScreenWeekDay): ElementNode {
  // Today is inverted rather than tinted: a solid block is the only emphasis
  // a 1-bit panel renders cleanly.
  const inverted = day.is_today;
  // A column is only 114px wide. The spaced en dash reads better in the main
  // block, but here it is the difference between fitting and clipping.
  const lines = day.is_closed
    ? ['—']
    : day.hours_text.split(' · ').map((slot) => slot.replace(' – ', '–'));

  return h(
    'div',
    {
      style: {
        display: 'flex',
        flexDirection: 'column',
        alignItems: 'center',
        justifyContent: 'center',
        flexGrow: 1,
        flexBasis: 0,
        paddingTop: 8,
        paddingBottom: 8,
        paddingLeft: 6,
        paddingRight: 6,
        backgroundColor: inverted ? BLACK : WHITE,
        color: inverted ? WHITE : BLACK,
      },
    },
    h(
      'div',
      { style: { display: 'flex', fontSize: 19, fontWeight: 700, marginBottom: 6 } },
      `${day.label_fr}${day.is_exception ? '*' : ''}`,
    ),
    ...lines.map((line) =>
      h('div', { style: { display: 'flex', fontSize: 16, lineHeight: 1.35 } }, line),
    ),
  );
}

function banner(payload: ScreenPayload): ElementNode | null {
  if (!payload.banner) {
    return null;
  }
  const { text_fr: fr, text_en: en } = payload.banner;
  return h(
    'div',
    {
      style: {
        display: 'flex',
        flexDirection: 'column',
        justifyContent: 'center',
        height: BANNER_HEIGHT,
        paddingLeft: PADDING,
        paddingRight: PADDING,
        backgroundColor: BLACK,
        color: WHITE,
      },
    },
    h('div', { style: { display: 'flex', fontSize: 25, fontWeight: 600 } }, fr),
    en ? h('div', { style: { display: 'flex', fontSize: 19, marginTop: 4 } }, en) : null,
  );
}

/** Renders the payload to an SVG string, exactly 800x480. */
export async function renderScreenSvg(payload: ScreenPayload): Promise<string> {
  const [fonts, logo] = await Promise.all([loadScreenFonts(), loadLogoDataUri()]);
  return satori(screenTree(payload, logo) as unknown as React.ReactNode, {
    width: SCREEN_WIDTH,
    height: SCREEN_HEIGHT,
    fonts,
  });
}