// Copyright (C) 2024 Rubén Beltrán del Río

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program. If not, see https://map.tranquil.systems.
import Cocoa
import SwiftUI

class MapTextEditorController: NSViewController {

  @Binding var document: MapDocument
  var highlightRanges: [Range<String.Index>] {
    didSet {
      updateHighlights()
    }
  }

  var selectedRange: Int {
    didSet {
      updateHighlights()
      focusOnResult()
    }
  }

  let onChange: () -> Void

  private let vertexRegex = MapParsingPatterns.vertex
  private let edgeRegex = MapParsingPatterns.edge
  private let blockerRegex = MapParsingPatterns.blocker
  private let opportunityRegex = MapParsingPatterns.opportunity
  private let noteRegex = MapParsingPatterns.note
  private let stageRegex = MapParsingPatterns.stage
  private let groupRegex = MapParsingPatterns.group

  private let changeDebouncer: Debouncer = Debouncer(seconds: 1)

  init(
    document: Binding<MapDocument>, highlightRanges: [Range<String.Index>], selectedRange: Int,
    onChange: @escaping () -> Void
  ) {
    self._document = document
    self.onChange = onChange
    self.highlightRanges = highlightRanges
    self.selectedRange = selectedRange
    super.init(nibName: nil, bundle: nil)
  }

  required init?(coder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }

  override func loadView() {
    let scrollView = NSTextView.scrollableTextView()
    let textView = scrollView.documentView as! NSTextView

    scrollView.translatesAutoresizingMaskIntoConstraints = false

    textView.backgroundColor = .UI.background
    textView.allowsUndo = true
    textView.delegate = self
    textView.textStorage?.delegate = self
    textView.string = self.document.text
    textView.isEditable = true
    textView.font = .monospacedSystemFont(ofSize: 16.0, weight: .regular)
    self.view = scrollView
  }

  override func viewDidAppear() {
    self.view.window?.makeFirstResponder(self.view)
    updateHighlights()
  }

  private var textView: NSTextView? {
    return (view as? NSScrollView)?.documentView as? NSTextView
  }

  private func updateHighlights() {
    if let textView {
      if let textStorage = textView.textStorage {
        textStorage.removeAttribute(
          .backgroundColor, range: NSRange(location: 0, length: textStorage.length))

        for (index, range) in highlightRanges.enumerated() {
          let nsRange = NSRange(range, in: textStorage.string)

          let color = index == selectedRange ? NSColor.Syntax.highlightMatch : NSColor.Syntax.match
          textStorage.addAttribute(.backgroundColor, value: color, range: nsRange)
        }

        textView.needsDisplay = true

      }
    }
  }

  private func focusOnResult() {
    if let textView {
      if let textStorage = textView.textStorage {
        if selectedRange < highlightRanges.count {
          let range = highlightRanges[selectedRange]
          let nsRange = NSRange(range, in: textStorage.string)
          textView.scrollRangeToVisible(nsRange)
        }
      }
    }
  }
}

extension MapTextEditorController: NSTextViewDelegate {

  func textDidChange(_ obj: Notification) {
    if let textField = obj.object as? NSTextView {
      self.document.text = textField.string

      changeDebouncer.debounce {
        DispatchQueue.main.async {
          self.onChange()
        }
      }
    }
  }

  func textView(_ view: NSTextView, shouldChangeTextIn: NSRange, replacementString: String?) -> Bool
  {
    let range = Range(shouldChangeTextIn, in: view.string)
    let target = view.string[range!]

    if target == "--" {
      return false
    }

    return true
  }
}

extension MapTextEditorController: NSTextStorageDelegate {

  override func textStorageDidProcessEditing(_ obj: Notification) {
    if let textStorage = obj.object as? NSTextStorage {
      self.colorizeText(textStorage: textStorage)
    }
  }

  private func colorizeText(textStorage: NSTextStorage) {
    let range = NSMakeRange(0, textStorage.length)
    var matches = vertexRegex.matches(in: textStorage.string, options: [], range: range)

    for match in matches {
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.vertex], range: match.range(at: 1))
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.number], range: match.range(at: 2))
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.number], range: match.range(at: 3))
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.option], range: match.range(at: 4))
    }

    matches = edgeRegex.matches(in: textStorage.string, options: [], range: range)

    for match in matches {
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.vertex], range: match.range(at: 1))
      let arrowRange = match.range(at: 2)
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.symbol],
        range: NSMakeRange(arrowRange.lowerBound - 1, arrowRange.length + 1))
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.vertex], range: match.range(at: 3))
    }

    matches = opportunityRegex.matches(in: textStorage.string, options: [], range: range)

    for match in matches {
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.option], range: match.range(at: 1))
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.vertex], range: match.range(at: 2))
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.symbol], range: match.range(at: 3))
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.number], range: match.range(at: 4))
    }

    matches = blockerRegex.matches(in: textStorage.string, options: [], range: range)

    for match in matches {
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.option], range: match.range(at: 1))
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.vertex], range: match.range(at: 2))
    }

    matches = noteRegex.matches(in: textStorage.string, options: [], range: range)

    for match in matches {
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.option], range: match.range(at: 1))
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.number], range: match.range(at: 2))
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.number], range: match.range(at: 3))
    }

    matches = stageRegex.matches(in: textStorage.string, options: [], range: range)

    for match in matches {
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.option], range: match.range(at: 1))
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.number], range: match.range(at: 2))
    }

    matches = groupRegex.matches(in: textStorage.string, options: [], range: range)

    for match in matches {
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.option], range: match.range(at: 1))
      textStorage.addAttributes(
        [.foregroundColor: NSColor.Syntax.vertex], range: match.range(at: 2))
    }
  }
}

struct MapTextEditor: NSViewControllerRepresentable {

  @Binding var document: MapDocument
  var highlightRanges: [Range<String.Index>]
  var selectedRange: Int
  var onChange: () -> Void = {}

  func makeNSViewController(
    context: NSViewControllerRepresentableContext<MapTextEditor>
  ) -> MapTextEditorController {
    return MapTextEditorController(
      document: $document, highlightRanges: highlightRanges, selectedRange: selectedRange,
      onChange: onChange)
  }

  func updateNSViewController(
    _ nsViewController: MapTextEditorController,
    context: NSViewControllerRepresentableContext<MapTextEditor>
  ) {
    nsViewController.highlightRanges = highlightRanges
    if nsViewController.selectedRange != selectedRange {
      nsViewController.selectedRange = selectedRange
    }
  }
}