const { getColor } = require('./themes')
const {
  ATTR_FG,
  ATTR_BG,
  ATTR_BOLD,
  ATTR_UNDERLINE,
  ATTR_BLINK,
  ATTR_ITALIC,
  ATTR_STRIKE,
  ATTR_OVERLINE,
  ATTR_FAINT,
  ATTR_FRAKTUR
} = require('./screen_attr_bits')

// debug toolbar, tooltip and screen
module.exports = function attachDebugger (screen, connection) {
  // debug screen overlay
  const debugCanvas = document.createElement('canvas')
  debugCanvas.classList.add('debug-canvas')
  const ctx = debugCanvas.getContext('2d')

  // debug toolbar
  const toolbar = document.createElement('div')
  toolbar.classList.add('debug-toolbar')

  // debug tooltip
  const tooltip = document.createElement('div')
  tooltip.classList.add('debug-tooltip')
  tooltip.classList.add('hidden')

  // update functions, defined somewhere below
  let updateTooltip
  let updateToolbar

  // tooltip cell
  let selectedCell = null

  // update tooltip cell when mouse moves
  const onMouseMove = (e) => {
    if (e.target !== screen.layout.canvas) {
      selectedCell = null
      return
    }
    selectedCell = screen.layout.screenToGrid(e.offsetX, e.offsetY)
    updateTooltip()
  }

  // hide tooltip when mouse leaves
  const onMouseOut = (e) => {
    selectedCell = null
    tooltip.classList.add('hidden')
  }

  // updates debug canvas size
  const updateCanvasSize = function () {
    let { width, height, devicePixelRatio } = screen.layout.window
    let cellSize = screen.layout.getCellSize()
    let padding = Math.round(screen.layout._padding)
    debugCanvas.width = (width * cellSize.width + 2 * padding) * devicePixelRatio
    debugCanvas.height = (height * cellSize.height + 2 * padding) * devicePixelRatio
    debugCanvas.style.width = `${width * cellSize.width + 2 * screen.layout._padding}px`
    debugCanvas.style.height = `${height * cellSize.height + 2 * screen.layout._padding}px`
  }

  // defined somewhere below
  let startDrawLoop

  let screenAttached = false

  // node to which events were bound (kept here for when they need to be removed)
  let eventNode

  // attaches/detaches debug screen overlay to/from DOM
  const setScreenAttached = function (attached) {
    if (attached && !debugCanvas.parentNode) {
      screen.layout.canvas.parentNode.appendChild(debugCanvas)
      eventNode = debugCanvas.parentNode
      eventNode.addEventListener('mousemove', onMouseMove)
      eventNode.addEventListener('mouseout', onMouseOut)
      screen.layout.on('size-update', updateCanvasSize)
      updateCanvasSize()
      screenAttached = true
      startDrawLoop()
    } else if (!attached && debugCanvas.parentNode) {
      debugCanvas.parentNode.removeChild(debugCanvas)
      eventNode.removeEventListener('mousemove', onMouseMove)
      eventNode.removeEventListener('mouseout', onMouseOut)
      screen.layout.removeListener('size-update', updateCanvasSize)
      screenAttached = false
    }
  }

  // attaches/detaches toolbar and tooltip to/from DOM
  const setToolbarAttached = function (attached) {
    if (attached && !toolbar.parentNode) {
      screen.layout.canvas.parentNode.appendChild(toolbar)
      screen.layout.canvas.parentNode.appendChild(tooltip)
      updateToolbar()
    } else if (!attached && toolbar.parentNode) {
      screen.layout.canvas.parentNode.removeChild(toolbar)
      screen.layout.canvas.parentNode.removeChild(tooltip)
    }
  }

  // attach/detach toolbar when debug mode is enabled/disabled
  screen.on('update-window:debug', enabled => {
    setToolbarAttached(enabled)
  })

  // ditto ^
  screen.layout.on('update-window:debug', enabled => {
    setScreenAttached(enabled)
  })

  let drawData = {
    // last draw reason
    reason: '',

    // when true, will show colored cell update overlays
    showUpdates: false,

    // draw start time in milliseconds
    startTime: 0,

    // end time
    endTime: 0,

    // partial update frames
    frames: [],

    // cell data
    cells: new Map(),

    // scroll region
    scrollRegion: null
  }

  // debug interface
  screen._debug = screen.layout.renderer._debug = {
    drawStart (reason) {
      drawData.reason = reason
      drawData.startTime = window.performance.now()
    },
    drawEnd () {
      drawData.endTime = window.performance.now()
    },
    setCell (cell, flags) {
      drawData.cells.set(cell, [flags, window.performance.now()])
    },
    pushFrame (frame) {
      drawData.frames.push([...frame, window.performance.now()])
    }
  }

  let isDrawing = false
  let drawLoop = function () {
    // draw while the screen is attached
    if (screenAttached) window.requestAnimationFrame(drawLoop)
    else isDrawing = false

    let now = window.performance.now()

    let { width, height, devicePixelRatio } = screen.layout.window
    let padding = Math.round(screen.layout._padding)
    let cellSize = screen.layout.getCellSize()

    ctx.setTransform(devicePixelRatio, 0, 0, devicePixelRatio, 0, 0)
    ctx.clearRect(0, 0, width * cellSize.width + 2 * padding, height * cellSize.height + 2 * padding)
    ctx.translate(padding, padding)

    ctx.lineWidth = 2
    ctx.lineJoin = 'round'

    if (drawData.showUpdates) {
      const cells = drawData.cells
      for (let cell = 0; cell < width * height; cell++) {
        // cell does not exist or has no flags set
        if (!cells.has(cell) || cells.get(cell)[0] === 0) continue

        const [flags, timestamp] = cells.get(cell)
        let elapsedTime = (now - timestamp) / 1000

        if (elapsedTime > 1) {
          cells.delete(cell)
          continue
        }

        ctx.globalAlpha = 0.5 * Math.max(0, 1 - elapsedTime)

        let x = cell % width
        let y = Math.floor(cell / width)

        if (flags & 2) {
          // updated
          ctx.fillStyle = '#0f0'
        } else if (flags & 1) {
          // redrawn
          ctx.fillStyle = '#f0f'
        }

        if (!(flags & 4)) {
          // outside a clipped region
          ctx.fillStyle = '#0ff'
        }

        if (flags & 16) {
          // was filled to speed up rendering
          ctx.globalAlpha /= 2
        }

        ctx.fillRect(x * cellSize.width, y * cellSize.height, cellSize.width, cellSize.height)

        if (flags & 8) {
          // wide cell
          ctx.strokeStyle = '#f00'
          ctx.beginPath()
          ctx.moveTo(x * cellSize.width, (y + 1) * cellSize.height)
          ctx.lineTo((x + 1) * cellSize.width, (y + 1) * cellSize.height)
          ctx.stroke()
        }
      }

      let framesToDelete = []
      for (let frame of drawData.frames) {
        let timestamp = frame[4]
        let elapsedTime = (now - timestamp) / 1000
        if (elapsedTime > 1) framesToDelete.push(frame)
        else {
          ctx.globalAlpha = 1 - elapsedTime
          ctx.strokeStyle = '#ff0'
          ctx.strokeRect(frame[0] * cellSize.width, frame[1] * cellSize.height,
            frame[2] * cellSize.width, frame[3] * cellSize.height)
        }
      }
      for (let frame of framesToDelete) {
        drawData.frames.splice(drawData.frames.indexOf(frame), 1)
      }
    }

    if (selectedCell !== null) {
      // draw a dashed outline around the selected cell
      let [x, y] = selectedCell

      ctx.save()
      ctx.globalAlpha = 0.5
      ctx.lineWidth = 1

      // draw X line
      ctx.beginPath()
      ctx.moveTo(0, y * cellSize.height)
      ctx.lineTo(x * cellSize.width, y * cellSize.height)
      ctx.strokeStyle = '#f00'
      ctx.setLineDash([cellSize.width])
      ctx.stroke()

      // draw Y line
      ctx.beginPath()
      ctx.moveTo(x * cellSize.width, 0)
      ctx.lineTo(x * cellSize.width, y * cellSize.height)
      ctx.strokeStyle = '#0f0'
      ctx.setLineDash([cellSize.height])
      ctx.stroke()

      ctx.globalAlpha = 1
      ctx.lineWidth = 1 + 0.5 * Math.sin((now / 1000) * 10)
      ctx.strokeStyle = '#fff'
      ctx.lineJoin = 'round'
      ctx.setLineDash([2, 2])
      ctx.lineDashOffset = (now / 1000) * 10
      ctx.strokeRect(x * cellSize.width, y * cellSize.height, cellSize.width, cellSize.height)
      ctx.lineDashOffset += 2
      ctx.strokeStyle = '#000'
      ctx.strokeRect(x * cellSize.width, y * cellSize.height, cellSize.width, cellSize.height)
      ctx.restore()
    }

    if (drawData.scrollRegion !== null) {
      // draw two lines marking the scroll region bounds
      let [start, end] = drawData.scrollRegion

      ctx.save()
      ctx.globalAlpha = 1
      ctx.strokeStyle = '#00f'
      ctx.lineWidth = 2
      ctx.setLineDash([2, 2])

      ctx.beginPath()
      ctx.moveTo(0, start * cellSize.height)
      ctx.lineTo(width * cellSize.width, start * cellSize.height)
      ctx.stroke()

      ctx.beginPath()
      ctx.moveTo(0, (end + 1) * cellSize.height)
      ctx.lineTo(width * cellSize.width, (end + 1) * cellSize.height)
      ctx.stroke()

      ctx.restore()
    }
  }

  startDrawLoop = function () {
    if (isDrawing) return
    isDrawing = true
    drawLoop()
  }

  let pad2 = i => ('00' + i.toString()).substr(-2)
  let formatColor = color => color < 256
    ? color.toString()
    : '#' + pad2(color >> 16) + pad2((color >> 8) & 0xFF) + pad2(color & 0xFF)

  let makeSpan = (text, styles) => {
    let span = document.createElement('span')
    span.textContent = text
    Object.assign(span.style, styles || {})
    return span
  }
  let formatAttributes = (target, attrs) => {
    if (attrs & ATTR_FG) target.appendChild(makeSpan('HasFG'))
    if (attrs & ATTR_BG) target.appendChild(makeSpan('HasBG'))
    if (attrs & ATTR_BOLD) target.appendChild(makeSpan('Bold', { fontWeight: 'bold' }))
    if (attrs & ATTR_UNDERLINE) target.appendChild(makeSpan('Uline', { textDecoration: 'underline' }))
    if (attrs & ATTR_BLINK) target.appendChild(makeSpan('Blink'))
    if (attrs & ATTR_ITALIC) target.appendChild(makeSpan('Italic', { fontStyle: 'italic' }))
    if (attrs & ATTR_STRIKE) target.appendChild(makeSpan('Strike', { textDecoration: 'line-through' }))
    if (attrs & ATTR_OVERLINE) target.appendChild(makeSpan('Oline', { textDecoration: 'overline' }))
    if (attrs & ATTR_FAINT) target.appendChild(makeSpan('Faint', { opacity: 0.5 }))
    if (attrs & ATTR_FRAKTUR) target.appendChild(makeSpan('Fraktur'))
  }

  updateTooltip = function () {
    // TODO: make this not destroy and recreate the same nodes every time
    tooltip.classList.remove('hidden')
    tooltip.innerHTML = ''
    let cell = selectedCell[1] * screen.window.width + selectedCell[0]
    if (!screen.screen[cell]) return

    let foreground = document.createElement('span')
    foreground.textContent = formatColor(screen.screenFG[cell])
    let preview = document.createElement('span')
    preview.textContent = ' ●'
    preview.style.color = getColor(screen.screenFG[cell], screen.layout.renderer.palette)
    foreground.appendChild(preview)

    let background = document.createElement('span')
    background.textContent = formatColor(screen.screenBG[cell])
    let bgPreview = document.createElement('span')
    bgPreview.textContent = ' ●'
    bgPreview.style.color = getColor(screen.screenBG[cell], screen.layout.renderer.palette)
    background.appendChild(bgPreview)

    let character = screen.screen[cell]
    let codePoint = character.codePointAt(0)
    let formattedCodePoint = codePoint.toString(16).length <= 4
      ? `0000${codePoint.toString(16)}`.substr(-4)
      : codePoint.toString(16)

    let attributes = document.createElement('span')
    attributes.classList.add('attributes')
    formatAttributes(attributes, screen.screenAttrs[cell])

    let data = {
      Cell: `col ${selectedCell[0] + 1}, ln ${selectedCell[1] + 1} (${cell})`,
      Foreground: foreground,
      Background: background,
      Character: `U+${formattedCodePoint}`,
      Attributes: attributes
    }

    let table = document.createElement('table')

    for (let name in data) {
      let row = document.createElement('tr')
      let label = document.createElement('td')
      label.appendChild(new window.Text(name))
      label.classList.add('label')

      let value = document.createElement('td')
      value.appendChild(typeof data[name] === 'string' ? new window.Text(data[name]) : data[name])
      value.classList.add('value')

      row.appendChild(label)
      row.appendChild(value)
      table.appendChild(row)
    }

    tooltip.appendChild(table)

    let cellSize = screen.layout.getCellSize()
    // add 3 to the position because for some reason the corner is off
    let posX = (selectedCell[0] + 1) * cellSize.width + 3
    let posY = (selectedCell[1] + 1) * cellSize.height + 3
    tooltip.style.transform = `translate(${posX}px, ${posY}px)`
  }

  let toolbarData = null
  let toolbarNodes = {}

  // construct the toolbar if it wasn't already
  const initToolbar = function () {
    if (toolbarData) return

    let showUpdates = document.createElement('input')
    showUpdates.type = 'checkbox'
    showUpdates.addEventListener('change', e => {
      drawData.showUpdates = showUpdates.checked
    })

    let fancyGraphics = document.createElement('input')
    fancyGraphics.type = 'checkbox'
    fancyGraphics.value = !!screen.layout.renderer.graphics
    fancyGraphics.addEventListener('change', e => {
      screen.layout.renderer.graphics = +fancyGraphics.checked
    })

    toolbarData = {
      cursor: {
        title: 'Cursor',
        Position: '',
        Style: '',
        Visible: true,
        Hanging: false
      },
      internal: {
        Flags: '',
        'Cursor Attributes': '',
        'Code Page': '',
        Heap: 0,
        Clients: 0
      },
      drawing: {
        title: 'Drawing',
        'Last Update': '',
        'Show Updates': showUpdates,
        'Fancy Graphics': fancyGraphics,
        'Redraw Screen': () => {
          screen.layout.renderer.resetDrawn()
          screen.layout.renderer.draw('debug-redraw')
        }
      }
    }

    for (let i in toolbarData) {
      let group = toolbarData[i]
      let table = document.createElement('table')
      table.classList.add('toolbar-group')

      toolbarNodes[i] = {}

      for (let key in group) {
        let item = document.createElement('tr')
        let name = document.createElement('td')
        name.classList.add('name')
        let value = document.createElement('td')
        value.classList.add('value')

        toolbarNodes[i][key] = { name, value }

        if (key === 'title') {
          name.textContent = group[key]
          name.classList.add('title')
        } else {
          name.textContent = key
          if (group[key] instanceof Function) {
            name.textContent = ''
            let button = document.createElement('button')
            name.classList.add('has-button')
            name.appendChild(button)
            button.textContent = key
            button.addEventListener('click', e => group[key](e))
          } else if (group[key] instanceof window.Node) value.appendChild(group[key])
          else value.textContent = group[key]
        }

        item.appendChild(name)
        item.appendChild(value)
        table.appendChild(item)
      }

      toolbar.appendChild(table)
    }

    let heartbeat = toolbarNodes.heartbeat = document.createElement('div')
    heartbeat.classList.add('heartbeat')
    heartbeat.textContent = '❤'
    toolbar.appendChild(heartbeat)
  }

  connection.on('heartbeat', () => {
    if (screenAttached && toolbarNodes.heartbeat) {
      toolbarNodes.heartbeat.classList.remove('beat')
      window.requestAnimationFrame(() => {
        toolbarNodes.heartbeat.classList.add('beat')
      })
    }
  })

  updateToolbar = function () {
    initToolbar()

    Object.assign(toolbarData.cursor, {
      Position: `col ${screen.cursor.x + 1}, ln ${screen.cursor.y + 1}`,
      Style: screen.cursor.style + (screen.cursor.blinking ? ', blink' : ''),
      Visible: screen.cursor.visible,
      Hanging: screen.cursor.hanging
    })

    let drawTime = Math.round((drawData.endTime - drawData.startTime) * 100) / 100
    toolbarData.drawing['Last Update'] = `${drawData.reason} (${drawTime}ms)`
    toolbarData.drawing['Fancy Graphics'].checked = !!screen.layout.renderer.graphics

    for (let i in toolbarData) {
      let group = toolbarData[i]
      let nodes = toolbarNodes[i]
      for (let key in group) {
        if (key === 'title') continue
        let value = nodes[key].value
        if (!(group[key] instanceof window.Node) && !(group[key] instanceof Function)) {
          value.textContent = group[key]
        }
      }
    }
  }

  screen.on('update', updateToolbar)
  screen.on('internal', data => {
    if (screenAttached && toolbarData) {
      Object.assign(toolbarData.internal, {
        Flags: data.flags.toString(2),
        'Cursor Attributes': data.cursorAttrs.toString(2),
        'Code Page': `${data.charsetGx} (${data.charsetG0}, ${data.charsetG1})`,
        Heap: data.freeHeap,
        Clients: data.clientCount
      })
      drawData.scrollRegion = [data.regionStart, data.regionEnd]
      updateToolbar()
    }
  })
}