import satori from 'satori'
import { Resvg } from '@resvg/resvg-js'

let fontCache

async function loadFonts() {
  if (fontCache) return fontCache
  const storage = useStorage('assets:server')
  const [brygadaRegular, brygadaSemiBold, commitRegular, commitBold] =
    await Promise.all([
      storage.getItemRaw('fonts/Brygada1918-Regular.ttf'),
      storage.getItemRaw('fonts/Brygada1918-SemiBold.ttf'),
      storage.getItemRaw('fonts/commit-mono-400.woff'),
      storage.getItemRaw('fonts/commit-mono-600.woff')
    ])
  fontCache = [
    { name: 'Brygada 1918', data: brygadaRegular, weight: 400, style: 'normal' },
    { name: 'Brygada 1918', data: brygadaSemiBold, weight: 600, style: 'normal' },
    { name: 'Commit Mono', data: commitRegular, weight: 400, style: 'normal' },
    { name: 'Commit Mono', data: commitBold, weight: 600, style: 'normal' }
  ]
  return fontCache
}

// Insert Cloudinary transform params (resize, quality) into the URL so we
// embed a smaller image and keep the resulting PNG under a reasonable size.
function withCloudinaryTransform(url) {
  if (typeof url !== 'string') return url
  return url.replace(
    /\/image\/upload\/(?!w_|h_|c_|q_|f_)/,
    '/image/upload/w_1200,h_340,c_fill,q_auto,f_jpg/'
  )
}

async function fetchImageAsDataUrl(url) {
  if (!url) return null
  try {
    const transformed = withCloudinaryTransform(url)
    const res = await fetch(transformed)
    if (!res.ok) return null
    const buf = Buffer.from(await res.arrayBuffer())
    const contentType = res.headers.get('content-type') || 'image/jpeg'
    return `data:${contentType};base64,${buf.toString('base64')}`
  } catch {
    return null
  }
}

function formatEventDate(startDate, timeZone) {
  const date = new Date(startDate)
  const dateFmt = new Intl.DateTimeFormat('en-US', {
    weekday: 'long',
    month: 'long',
    day: 'numeric',
    timeZone
  }).format(date)
  const timeFmt = new Intl.DateTimeFormat('en-US', {
    hour: 'numeric',
    minute: '2-digit',
    timeZoneName: 'short',
    timeZone
  }).format(date)
  return `${dateFmt} · ${timeFmt}`
}

// Design tokens lifted from app/assets/css/main.css (light palette).
// Hardcoded here because satori doesn't resolve CSS variables.
const COLOR = {
  bg: '#f4efe4',
  textBright: '#1a1008',
  textDim: '#5a5040',
  candle: '#7a5a10',
  border: '#b8a880',
  parch: '#2a2015',
  parchText: '#ede4d0',
  parchAccent: '#c4a448'
}

function buildTemplate({ title, dateLabel, imageDataUrl }) {
  const hasImage = Boolean(imageDataUrl)

  const imageBlock = hasImage
    ? {
        type: 'div',
        props: {
          style: {
            display: 'flex',
            width: '100%',
            height: 340,
            overflow: 'hidden',
            borderBottom: `2px dashed ${COLOR.border}`
          },
          children: {
            type: 'img',
            props: {
              src: imageDataUrl,
              width: 1200,
              height: 340,
              style: { width: '100%', height: '100%', objectFit: 'cover' }
            }
          }
        }
      }
    : {
        type: 'div',
        props: {
          style: {
            display: 'flex',
            width: '100%',
            height: 340,
            background: COLOR.parch,
            alignItems: 'center',
            justifyContent: 'center',
            borderBottom: `2px dashed ${COLOR.border}`
          },
          children: {
            type: 'div',
            props: {
              style: {
                fontFamily: 'Brygada 1918',
                fontSize: 64,
                fontWeight: 600,
                color: COLOR.parchText,
                letterSpacing: '-0.01em'
              },
              children: 'GHOST GUILD'
            }
          }
        }
      }

  return {
    type: 'div',
    props: {
      style: {
        display: 'flex',
        flexDirection: 'column',
        width: 1200,
        height: 630,
        background: COLOR.bg,
        fontFamily: 'Commit Mono'
      },
      children: [
        imageBlock,
        {
          type: 'div',
          props: {
            style: {
              display: 'flex',
              flexDirection: 'column',
              padding: '36px 60px 48px 60px',
              flex: 1,
              justifyContent: 'space-between'
            },
            children: [
              {
                type: 'div',
                props: {
                  style: {
                    display: 'flex',
                    flexDirection: 'column',
                    gap: 18
                  },
                  children: [
                    {
                      type: 'div',
                      props: {
                        style: {
                          fontFamily: 'Commit Mono',
                          fontSize: 18,
                          fontWeight: 600,
                          color: COLOR.candle,
                          letterSpacing: '0.12em',
                          textTransform: 'uppercase'
                        },
                        children: 'Ghost Guild · Event'
                      }
                    },
                    {
                      type: 'div',
                      props: {
                        style: {
                          fontFamily: 'Brygada 1918',
                          fontSize: 56,
                          fontWeight: 600,
                          color: COLOR.textBright,
                          lineHeight: 1.1,
                          letterSpacing: '-0.01em',
                          maxHeight: 140,
                          overflow: 'hidden'
                        },
                        children: title
                      }
                    }
                  ]
                }
              },
              {
                type: 'div',
                props: {
                  style: {
                    fontFamily: 'Commit Mono',
                    fontSize: 22,
                    color: COLOR.textDim
                  },
                  children: dateLabel
                }
              }
            ]
          }
        }
      ]
    }
  }
}

export async function renderEventOG(event) {
  const fonts = await loadFonts()
  const imageDataUrl = event.featureImage?.url
    ? await fetchImageAsDataUrl(event.featureImage.url)
    : null
  const dateLabel = formatEventDate(
    event.startDate,
    event.displayTimezone || 'America/Toronto'
  )

  const svg = await satori(
    buildTemplate({ title: event.title, dateLabel, imageDataUrl }),
    { width: 1200, height: 630, fonts }
  )

  const png = new Resvg(svg, {
    fitTo: { mode: 'width', value: 1200 }
  })
    .render()
    .asPng()

  return png
}