text: import { indexOf, lst } from "../util/misc"
  
  import { cmp } from "./pos"
  import { sawCollapsedSpans } from "./saw_special_spans"
  import { getLine, isLine, lineNo } from "./utils_line"
  
  // TEXTMARKER SPANS
  
  export function MarkedSpan(marker, from, to) {
    this.marker = marker
    this.from = from; this.to = to
  }
  
  // Search an array of spans for a span matching the given marker.
  export function getMarkedSpanFor(spans, marker) {
    if (spans) for (let i = 0; i < spans.length; ++i) {
      let span = spans[i]
      if (span.marker == marker) return span
    }
  }
  // Remove a span from an array, returning undefined if no spans are
  // left (we don't store arrays for lines without spans).
  export function removeMarkedSpan(spans, span) {
    let r
    for (let i = 0; i < spans.length; ++i)
      if (spans[i] != span) (r || (r = [])).push(spans[i])
    return r
  }
  // Add a span to a line.
  export function addMarkedSpan(line, span) {
    line.markedSpans = line.markedSpans ? line.markedSpans.concat([span]) : [span]
    span.marker.attachLine(line)
  }
  
  // Used for the algorithm that adjusts markers for a change in the
  // document. These functions cut an array of spans at a given
  // character position, returning an array of remaining chunks (or
  // undefined if nothing remains).
  function markedSpansBefore(old, startCh, isInsert) {
    let nw
    if (old) for (let i = 0; i < old.length; ++i) {
      let span = old[i], marker = span.marker
      let startsBefore = span.from == null || (marker.inclusiveLeft ? span.from <= startCh : span.from < startCh)
      if (startsBefore || span.from == startCh && marker.type == "bookmark" && (!isInsert || !span.marker.insertLeft)) {
        let endsAfter = span.to == null || (marker.inclusiveRight ? span.to >= startCh : span.to > startCh)
        ;(nw || (nw = [])).push(new MarkedSpan(marker, span.from, endsAfter ? null : span.to))
      }
    }
    return nw
  }
  function markedSpansAfter(old, endCh, isInsert) {
    let nw
    if (old) for (let i = 0; i < old.length; ++i) {
      let span = old[i], marker = span.marker
      let endsAfter = span.to == null || (marker.inclusiveRight ? span.to >= endCh : span.to > endCh)
      if (endsAfter || span.from == endCh && marker.type == "bookmark" && (!isInsert || span.marker.insertLeft)) {
        let startsBefore = span.from == null || (marker.inclusiveLeft ? span.from <= endCh : span.from < endCh)
        ;(nw || (nw = [])).push(new MarkedSpan(marker, startsBefore ? null : span.from - endCh,
                                              span.to == null ? null : span.to - endCh))
      }
    }
    return nw
  }
  
  // Given a change object, compute the new set of marker spans that
  // cover the line in which the change took place. Removes spans
  // entirely within the change, reconnects spans belonging to the
  // same marker that appear on both sides of the change, and cuts off
  // spans partially within the change. Returns an array of span
  // arrays with one element for each line in (after) the change.
  export function stretchSpansOverChange(doc, change) {
    if (change.full) return null
    let oldFirst = isLine(doc, change.from.line) && getLine(doc, change.from.line).markedSpans
    let oldLast = isLine(doc, change.to.line) && getLine(doc, change.to.line).markedSpans
    if (!oldFirst && !oldLast) return null
  
    let startCh = change.from.ch, endCh = change.to.ch, isInsert = cmp(change.from, change.to) == 0
    // Get the spans that 'stick out' on both sides
    let first = markedSpansBefore(oldFirst, startCh, isInsert)
    let last = markedSpansAfter(oldLast, endCh, isInsert)
  
    // Next, merge those two ends
    let sameLine = change.text.length == 1, offset = lst(change.text).length + (sameLine ? startCh : 0)
    if (first) {
      // Fix up .to properties of first
      for (let i = 0; i < first.length; ++i) {
        let span = first[i]
        if (span.to == null) {
          let found = getMarkedSpanFor(last, span.marker)
          if (!found) span.to = startCh
          else if (sameLine) span.to = found.to == null ? null : found.to + offset
        }
      }
    }
    if (last) {
      // Fix up .from in last (or move them into first in case of sameLine)
      for (let i = 0; i < last.length; ++i) {
        let span = last[i]
        if (span.to != null) span.to += offset
        if (span.from == null) {
          let found = getMarkedSpanFor(first, span.marker)
          if (!found) {
            span.from = offset
            if (sameLine) (first || (first = [])).push(span)
          }
        } else {
          span.from += offset
          if (sameLine) (first || (first = [])).push(span)
        }
      }
    }
    // Make sure we didn't create any zero-length spans
    if (first) first = clearEmptySpans(first)
    if (last && last != first) last = clearEmptySpans(last)
  
    let newMarkers = [first]
    if (!sameLine) {
      // Fill gap with whole-line-spans
      let gap = change.text.length - 2, gapMarkers
      if (gap > 0 && first)
        for (let i = 0; i < first.length; ++i)
          if (first[i].to == null)
            (gapMarkers || (gapMarkers = [])).push(new MarkedSpan(first[i].marker, null, null))
      for (let i = 0; i < gap; ++i)
        newMarkers.push(gapMarkers)
      newMarkers.push(last)
    }
    return newMarkers
  }
  
  // Remove spans that are empty and don't have a clearWhenEmpty
  // option of false.
  function clearEmptySpans(spans) {
    for (let i = 0; i < spans.length; ++i) {
      let span = spans[i]
      if (span.from != null && span.from == span.to && span.marker.clearWhenEmpty !== false)
        spans.splice(i--, 1)
    }
    if (!spans.length) return null
    return spans
  }
  
  // Used to 'clip' out readOnly ranges when making a change.
  export function removeReadOnlyRanges(doc, from, to) {
    let markers = null
    doc.iter(from.line, to.line + 1, function(line) {
      if (line.markedSpans) for (let i = 0; i < line.markedSpans.length; ++i) {
        let mark = line.markedSpans[i].marker
        if (mark.readOnly && (!markers || indexOf(markers, mark) == -1))
          (markers || (markers = [])).push(mark)
      }
    })
    if (!markers) return null
    let parts = [{from: from, to: to}]
    for (let i = 0; i < markers.length; ++i) {
      let mk = markers[i], m = mk.find(0)
      for (let j = 0; j < parts.length; ++j) {
        let p = parts[j]
        if (cmp(p.to, m.from) < 0 || cmp(p.from, m.to) > 0) continue
        let newParts = [j, 1], dfrom = cmp(p.from, m.from), dto = cmp(p.to, m.to)
        if (dfrom < 0 || !mk.inclusiveLeft && !dfrom)
          newParts.push({from: p.from, to: m.from})
        if (dto > 0 || !mk.inclusiveRight && !dto)
          newParts.push({from: m.to, to: p.to})
        parts.splice.apply(parts, newParts)
        j += newParts.length - 1
      }
    }
    return parts
  }
  
  // Connect or disconnect spans from a line.
  export function detachMarkedSpans(line) {
    let spans = line.markedSpans
    if (!spans) return
    for (let i = 0; i < spans.length; ++i)
      spans[i].marker.detachLine(line)
    line.markedSpans = null
  }
  export function attachMarkedSpans(line, spans) {
    if (!spans) return
    for (let i = 0; i < spans.length; ++i)
      spans[i].marker.attachLine(line)
    line.markedSpans = spans
  }
  
  // Helpers used when computing which overlapping collapsed span
  // counts as the larger one.
  function extraLeft(marker) { return marker.inclusiveLeft ? -1 : 0 }
  function extraRight(marker) { return marker.inclusiveRight ? 1 : 0 }
  
  // Returns a number indicating which of two overlapping collapsed
  // spans is larger (and thus includes the other). Falls back to
  // comparing ids when the spans cover exactly the same range.
  export function compareCollapsedMarkers(a, b) {
    let lenDiff = a.lines.length - b.lines.length
    if (lenDiff != 0) return lenDiff
    let aPos = a.find(), bPos = b.find()
    let fromCmp = cmp(aPos.from, bPos.from) || extraLeft(a) - extraLeft(b)
    if (fromCmp) return -fromCmp
    let toCmp = cmp(aPos.to, bPos.to) || extraRight(a) - extraRight(b)
    if (toCmp) return toCmp
    return b.id - a.id
  }
  
  // Find out whether a line ends or starts in a collapsed span. If
  // so, return the marker for that span.
  function collapsedSpanAtSide(line, start) {
    let sps = sawCollapsedSpans && line.markedSpans, found
    if (sps) for (let sp, i = 0; i < sps.length; ++i) {
      sp = sps[i]
      if (sp.marker.collapsed && (start ? sp.from : sp.to) == null &&
          (!found || compareCollapsedMarkers(found, sp.marker) < 0))
        found = sp.marker
    }
    return found
  }
  export function collapsedSpanAtStart(line) { return collapsedSpanAtSide(line, true) }
  export function collapsedSpanAtEnd(line) { return collapsedSpanAtSide(line, false) }
  
  // Test whether there exists a collapsed span that partially
  // overlaps (covers the start or end, but not both) of a new span.
  // Such overlap is not allowed.
  export function conflictingCollapsedRange(doc, lineNo, from, to, marker) {
    let line = getLine(doc, lineNo)
    let sps = sawCollapsedSpans && line.markedSpans
    if (sps) for (let i = 0; i < sps.length; ++i) {
      let sp = sps[i]
      if (!sp.marker.collapsed) continue
      let found = sp.marker.find(0)
      let fromCmp = cmp(found.from, from) || extraLeft(sp.marker) - extraLeft(marker)
      let toCmp = cmp(found.to, to) || extraRight(sp.marker) - extraRight(marker)
      if (fromCmp >= 0 && toCmp <= 0 || fromCmp <= 0 && toCmp >= 0) continue
      if (fromCmp <= 0 && (sp.marker.inclusiveRight && marker.inclusiveLeft ? cmp(found.to, from) >= 0 : cmp(found.to, from) > 0) ||
          fromCmp >= 0 && (sp.marker.inclusiveRight && marker.inclusiveLeft ? cmp(found.from, to) <= 0 : cmp(found.from, to) < 0))
        return true
    }
  }
  
  // A visual line is a line as drawn on the screen. Folding, for
  // example, can cause multiple logical lines to appear on the same
  // visual line. This finds the start of the visual line that the
  // given line is part of (usually that is the line itself).
  export function visualLine(line) {
    let merged
    while (merged = collapsedSpanAtStart(line))
      line = merged.find(-1, true).line
    return line
  }
  
  // Returns an array of logical lines that continue the visual line
  // started by the argument, or undefined if there are no such lines.
  export function visualLineContinued(line) {
    let merged, lines
    while (merged = collapsedSpanAtEnd(line)) {
      line = merged.find(1, true).line
      ;(lines || (lines = [])).push(line)
    }
    return lines
  }
  
  // Get the line number of the start of the visual line that the
  // given line number is part of.
  export function visualLineNo(doc, lineN) {
    let line = getLine(doc, lineN), vis = visualLine(line)
    if (line == vis) return lineN
    return lineNo(vis)
  }
  
  // Get the line number of the start of the next visual line after
  // the given line.
  export function visualLineEndNo(doc, lineN) {
    if (lineN > doc.lastLine()) return lineN
    let line = getLine(doc, lineN), merged
    if (!lineIsHidden(doc, line)) return lineN
    while (merged = collapsedSpanAtEnd(line))
      line = merged.find(1, true).line
    return lineNo(line) + 1
  }
  
  // Compute whether a line is hidden. Lines count as hidden when they
  // are part of a visual line that starts with another line, or when
  // they are entirely covered by collapsed, non-widget span.
  export function lineIsHidden(doc, line) {
    let sps = sawCollapsedSpans && line.markedSpans
    if (sps) for (let sp, i = 0; i < sps.length; ++i) {
      sp = sps[i]
      if (!sp.marker.collapsed) continue
      if (sp.from == null) return true
      if (sp.marker.widgetNode) continue
      if (sp.from == 0 && sp.marker.inclusiveLeft && lineIsHiddenInner(doc, line, sp))
        return true
    }
  }
  function lineIsHiddenInner(doc, line, span) {
    if (span.to == null) {
      let end = span.marker.find(1, true)
      return lineIsHiddenInner(doc, end.line, getMarkedSpanFor(end.line.markedSpans, span.marker))
    }
    if (span.marker.inclusiveRight && span.to == line.text.length)
      return true
    for (let sp, i = 0; i < line.markedSpans.length; ++i) {
      sp = line.markedSpans[i]
      if (sp.marker.collapsed && !sp.marker.widgetNode && sp.from == span.to &&
          (sp.to == null || sp.to != span.from) &&
          (sp.marker.inclusiveLeft || span.marker.inclusiveRight) &&
          lineIsHiddenInner(doc, line, sp)) return true
    }
  }
  
  // Find the height above the given line.
  export function heightAtLine(lineObj) {
    lineObj = visualLine(lineObj)
  
    let h = 0, chunk = lineObj.parent
    for (let i = 0; i < chunk.lines.length; ++i) {
      let line = chunk.lines[i]
      if (line == lineObj) break
      else h += line.height
    }
    for (let p = chunk.parent; p; chunk = p, p = chunk.parent) {
      for (let i = 0; i < p.children.length; ++i) {
        let cur = p.children[i]
        if (cur == chunk) break
        else h += cur.height
      }
    }
    return h
  }
  
  // Compute the character length of a line, taking into account
  // collapsed ranges (see markText) that might hide parts, and join
  // other lines onto it.
  export function lineLength(line) {
    if (line.height == 0) return 0
    let len = line.text.length, merged, cur = line
    while (merged = collapsedSpanAtStart(cur)) {
      let found = merged.find(0, true)
      cur = found.from.line
      len += found.from.ch - found.to.ch
    }
    cur = line
    while (merged = collapsedSpanAtEnd(cur)) {
      let found = merged.find(0, true)
      len -= cur.text.length - found.from.ch
      cur = found.to.line
      len += cur.text.length - found.to.ch
    }
    return len
  }
  
  // Find the longest line in the document.
  export function findMaxLine(cm) {
    let d = cm.display, doc = cm.doc
    d.maxLine = getLine(doc, doc.first)
    d.maxLineLength = lineLength(d.maxLine)
    d.maxLineChanged = true
    doc.iter(function(line) {
      let len = lineLength(line)
      if (len > d.maxLineLength) {
        d.maxLineLength = len
        d.maxLine = line
      }
    })
  }
  