import { buildLineContent } from "../line/line_data"
import { lineNumberFor } from "../line/utils_line"
import { ie, ie_version } from "../util/browser"
import { elt } from "../util/dom"
import { signalLater } from "../util/operation_group"

// When an aspect of a line changes, a string is added to
// lineView.changes. This updates the relevant part of the line's
// DOM structure.
export function updateLineForChanges(cm, lineView, lineN, dims) {
  for (let j = 0; j < lineView.changes.length; j++) {
    let type = lineView.changes[j]
    if (type == "text") updateLineText(cm, lineView)
    else if (type == "gutter") updateLineGutter(cm, lineView, lineN, dims)
    else if (type == "class") updateLineClasses(lineView)
    else if (type == "widget") updateLineWidgets(cm, lineView, dims)
  }
  lineView.changes = null
}

// Lines with gutter elements, widgets or a background class need to
// be wrapped, and have the extra elements added to the wrapper div
function ensureLineWrapped(lineView) {
  if (lineView.node == lineView.text) {
    lineView.node = elt("div", null, null, "position: relative")
    if (lineView.text.parentNode)
      lineView.text.parentNode.replaceChild(lineView.node, lineView.text)
    lineView.node.appendChild(lineView.text)
    if (ie && ie_version < 8) lineView.node.style.zIndex = 2
  }
  return lineView.node
}

function updateLineBackground(lineView) {
  let cls = lineView.bgClass ? lineView.bgClass + " " + (lineView.line.bgClass || "") : lineView.line.bgClass
  if (cls) cls += " CodeMirror-linebackground"
  if (lineView.background) {
    if (cls) lineView.background.className = cls
    else { lineView.background.parentNode.removeChild(lineView.background); lineView.background = null }
  } else if (cls) {
    let wrap = ensureLineWrapped(lineView)
    lineView.background = wrap.insertBefore(elt("div", null, cls), wrap.firstChild)
  }
}

// Wrapper around buildLineContent which will reuse the structure
// in display.externalMeasured when possible.
function getLineContent(cm, lineView) {
  let ext = cm.display.externalMeasured
  if (ext && ext.line == lineView.line) {
    cm.display.externalMeasured = null
    lineView.measure = ext.measure
    return ext.built
  }
  return buildLineContent(cm, lineView)
}

// Redraw the line's text. Interacts with the background and text
// classes because the mode may output tokens that influence these
// classes.
function updateLineText(cm, lineView) {
  let cls = lineView.text.className
  let built = getLineContent(cm, lineView)
  if (lineView.text == lineView.node) lineView.node = built.pre
  lineView.text.parentNode.replaceChild(built.pre, lineView.text)
  lineView.text = built.pre
  if (built.bgClass != lineView.bgClass || built.textClass != lineView.textClass) {
    lineView.bgClass = built.bgClass
    lineView.textClass = built.textClass
    updateLineClasses(lineView)
  } else if (cls) {
    lineView.text.className = cls
  }
}

function updateLineClasses(lineView) {
  updateLineBackground(lineView)
  if (lineView.line.wrapClass)
    ensureLineWrapped(lineView).className = lineView.line.wrapClass
  else if (lineView.node != lineView.text)
    lineView.node.className = ""
  let textClass = lineView.textClass ? lineView.textClass + " " + (lineView.line.textClass || "") : lineView.line.textClass
  lineView.text.className = textClass || ""
}

function updateLineGutter(cm, lineView, lineN, dims) {
  if (lineView.gutter) {
    lineView.node.removeChild(lineView.gutter)
    lineView.gutter = null
  }
  if (lineView.gutterBackground) {
    lineView.node.removeChild(lineView.gutterBackground)
    lineView.gutterBackground = null
  }
  if (lineView.line.gutterClass) {
    let wrap = ensureLineWrapped(lineView)
    lineView.gutterBackground = elt("div", null, "CodeMirror-gutter-background " + lineView.line.gutterClass,
                                    `left: ${cm.options.fixedGutter ? dims.fixedPos : -dims.gutterTotalWidth}px; width: ${dims.gutterTotalWidth}px`)
    wrap.insertBefore(lineView.gutterBackground, lineView.text)
  }
  let markers = lineView.line.gutterMarkers
  if (cm.options.lineNumbers || markers) {
    let wrap = ensureLineWrapped(lineView)
    let gutterWrap = lineView.gutter = elt("div", null, "CodeMirror-gutter-wrapper", `left: ${cm.options.fixedGutter ? dims.fixedPos : -dims.gutterTotalWidth}px`)
    cm.display.input.setUneditable(gutterWrap)
    wrap.insertBefore(gutterWrap, lineView.text)
    if (lineView.line.gutterClass)
      gutterWrap.className += " " + lineView.line.gutterClass
    if (cm.options.lineNumbers && (!markers || !markers["CodeMirror-linenumbers"]))
      lineView.lineNumber = gutterWrap.appendChild(
        elt("div", lineNumberFor(cm.options, lineN),
            "CodeMirror-linenumber CodeMirror-gutter-elt",
            `left: ${dims.gutterLeft["CodeMirror-linenumbers"]}px; width: ${cm.display.lineNumInnerWidth}px`))
    if (markers) for (let k = 0; k < cm.options.gutters.length; ++k) {
      let id = cm.options.gutters[k], found = markers.hasOwnProperty(id) && markers[id]
      if (found)
        gutterWrap.appendChild(elt("div", [found], "CodeMirror-gutter-elt",
                                   `left: ${dims.gutterLeft[id]}px; width: ${dims.gutterWidth[id]}px`))
    }
  }
}

function updateLineWidgets(cm, lineView, dims) {
  if (lineView.alignable) lineView.alignable = null
  for (let node = lineView.node.firstChild, next; node; node = next) {
    next = node.nextSibling
    if (node.className == "CodeMirror-linewidget")
      lineView.node.removeChild(node)
  }
  insertLineWidgets(cm, lineView, dims)
}

// Build a line's DOM representation from scratch
export function buildLineElement(cm, lineView, lineN, dims) {
  let built = getLineContent(cm, lineView)
  lineView.text = lineView.node = built.pre
  if (built.bgClass) lineView.bgClass = built.bgClass
  if (built.textClass) lineView.textClass = built.textClass

  updateLineClasses(lineView)
  updateLineGutter(cm, lineView, lineN, dims)
  insertLineWidgets(cm, lineView, dims)
  return lineView.node
}

// A lineView may contain multiple logical lines (when merged by
// collapsed spans). The widgets for all of them need to be drawn.
function insertLineWidgets(cm, lineView, dims) {
  insertLineWidgetsFor(cm, lineView.line, lineView, dims, true)
  if (lineView.rest) for (let i = 0; i < lineView.rest.length; i++)
    insertLineWidgetsFor(cm, lineView.rest[i], lineView, dims, false)
}

function insertLineWidgetsFor(cm, line, lineView, dims, allowAbove) {
  if (!line.widgets) return
  let wrap = ensureLineWrapped(lineView)
  for (let i = 0, ws = line.widgets; i < ws.length; ++i) {
    let widget = ws[i], node = elt("div", [widget.node], "CodeMirror-linewidget")
    if (!widget.handleMouseEvents) node.setAttribute("cm-ignore-events", "true")
    positionLineWidget(widget, node, lineView, dims)
    cm.display.input.setUneditable(node)
    if (allowAbove && widget.above)
      wrap.insertBefore(node, lineView.gutter || lineView.text)
    else
      wrap.appendChild(node)
    signalLater(widget, "redraw")
  }
}

function positionLineWidget(widget, node, lineView, dims) {
  if (widget.noHScroll) {
    ;(lineView.alignable || (lineView.alignable = [])).push(node)
    let width = dims.wrapperWidth
    node.style.left = dims.fixedPos + "px"
    if (!widget.coverGutter) {
      width -= dims.gutterTotalWidth
      node.style.paddingLeft = dims.gutterTotalWidth + "px"
    }
    node.style.width = width + "px"
  }
  if (widget.coverGutter) {
    node.style.zIndex = 5
    node.style.position = "relative"
    if (!widget.noHScroll) node.style.marginLeft = -dims.gutterTotalWidth + "px"
  }
}
