import { moveUp, moveDown, moveLeft, moveRight } from "./cursor.js";
import { hasSelection, selectedRange, clearSelection, deleteSelection } from "./selection.js";
import { elementToPos } from "./mouse.js";

export function setupInput(buffer, cursor, selection, onChange) {
  let isMouseDown = false;

  function startDrag(e) {
    if (!e.target.closest("#text")) return;
    isMouseDown = true;
    const pos = elementToPos(e.clientX, e.clientY, buffer);
    cursor.line = pos.line;
    cursor.col = pos.col;
    selection.anchor = { ...pos };
    selection.head = { ...pos };
    onChange();
  }

  function drag(e) {
    if (!isMouseDown) return;
    const pos = elementToPos(e.clientX, e.clientY, buffer);
    cursor.line = pos.line;
    cursor.col = pos.col;
    selection.head = { ...pos };
    onChange();
  }

  function endDrag() {
    isMouseDown = false;
  }

  function selectWord(e) {
    if (!e.target.closest("#text")) return;
    const pos = elementToPos(e.clientX, e.clientY, buffer);
    const line = buffer[pos.line];
    let start = pos.col;
    let end = pos.col;
    while (start > 0 && /\w/.test(line[start - 1])) start--;
    while (end < line.length && /\w/.test(line[end])) end++;
    cursor.line = pos.line;
    cursor.col = end;
    selection.anchor = { line: pos.line, col: start };
    selection.head = { line: pos.line, col: end };
    onChange();
  }

  function moveCursor(newLine, newCol, extending) {
    if (extending) {
      if (selection.anchor === null)
        selection.anchor = { line: cursor.line, col: cursor.col };
      selection.head = { line: newLine, col: newCol };
    } else {
      clearSelection(selection);
    }
    cursor.line = newLine;
    cursor.col = newCol;
  }

  function getSelectedText() {
    const range = selectedRange(selection);
    if (!range) return "";
    const { start, end } = range;
    if (start.line === end.line)
      return buffer[start.line].slice(start.col, end.col);
    const lines = [buffer[start.line].slice(start.col)];
    for (let i = start.line + 1; i < end.line; i++)
      lines.push(buffer[i]);
    lines.push(buffer[end.line].slice(0, end.col));
    return lines.join("\n");
  }

  function insertText(text) {
    if (hasSelection(selection)) deleteSelection(buffer, cursor, selection);
    const pasteLines = text.split("\n");
    const line = buffer[cursor.line];
    const before = line.slice(0, cursor.col);
    const after = line.slice(cursor.col);
    buffer[cursor.line] = before + pasteLines[0] + after;
    for (let i = 1; i < pasteLines.length; i++)
      buffer.splice(cursor.line + i, 0, pasteLines[i]);
    cursor.line += pasteLines.length - 1;
    cursor.col = pasteLines[pasteLines.length - 1].length +
      (pasteLines.length === 1 ? before.length : 0);
    clearSelection(selection);
  }

  function selectAll() {
    selection.anchor = { line: 0, col: 0 };
    selection.head = { line: buffer.length - 1, col: buffer[buffer.length - 1].length };
    cursor.line = buffer.length - 1;
    cursor.col = buffer[buffer.length - 1].length;
  }

  document.addEventListener("mousedown", startDrag);
  document.addEventListener("mousemove", drag);
  document.addEventListener("mouseup", endDrag);
  document.addEventListener("dblclick", selectWord);

  document.addEventListener("paste", (e) => {
    e.preventDefault();
    const text = e.clipboardData.getData("text");
    if (!text) return;
    insertText(text);
    onChange();
  });

  document.addEventListener("keydown", (e) => {
    const mod = e.ctrlKey || e.metaKey;
    const extending = e.shiftKey;

    if (mod) {
      if (e.key === "c") {
        e.preventDefault();
        const text = getSelectedText();
        if (text) navigator.clipboard.writeText(text);
        return;
      }
      if (e.key === "x") {
        e.preventDefault();
        const text = getSelectedText();
        if (text) navigator.clipboard.writeText(text);
        deleteSelection(buffer, cursor, selection);
        onChange();
        return;
      }
      if (e.key === "v") {
        return;
      }
      if (e.key === "a") {
        e.preventDefault();
        selectAll();
        onChange();
        return;
      }
      return;
    }

    if (e.key === "ArrowUp") {
      e.preventDefault();
      const newLine = Math.max(0, cursor.line - 1);
      const newCol = Math.min(cursor.col, buffer[newLine].length);
      moveCursor(newLine, newCol, extending);
      onChange();
      return;
    }
    if (e.key === "ArrowDown") {
      e.preventDefault();
      const newLine = Math.min(buffer.length - 1, cursor.line + 1);
      const newCol = Math.min(cursor.col, buffer[newLine].length);
      moveCursor(newLine, newCol, extending);
      onChange();
      return;
    }
    if (e.key === "ArrowLeft") {
      e.preventDefault();
      let newLine = cursor.line;
      let newCol = cursor.col;
      if (newCol > 0) newCol--;
      else if (newLine > 0) { newLine--; newCol = buffer[newLine].length; }
      moveCursor(newLine, newCol, extending);
      onChange();
      return;
    }
    if (e.key === "ArrowRight") {
      e.preventDefault();
      let newLine = cursor.line;
      let newCol = cursor.col;
      if (newCol < buffer[cursor.line].length) newCol++;
      else if (newLine < buffer.length - 1) { newLine++; newCol = 0; }
      moveCursor(newLine, newCol, extending);
      onChange();
      return;
    }
    if (e.key === "Backspace") {
      e.preventDefault();
      if (hasSelection(selection)) {
        deleteSelection(buffer, cursor, selection);
      } else if (cursor.col > 0) {
        const line = buffer[cursor.line];
        buffer[cursor.line] = line.slice(0, cursor.col - 1) + line.slice(cursor.col);
        cursor.col--;
      } else if (cursor.line > 0) {
        cursor.col = buffer[cursor.line - 1].length;
        buffer[cursor.line - 1] += buffer[cursor.line];
        buffer.splice(cursor.line, 1);
        cursor.line--;
      }
      clearSelection(selection);
      onChange();
      return;
    }
    if (e.key === "Enter") {
      e.preventDefault();
      if (hasSelection(selection)) deleteSelection(buffer, cursor, selection);
      const line = buffer[cursor.line];
      const rest = line.slice(cursor.col);
      buffer[cursor.line] = line.slice(0, cursor.col);
      buffer.splice(cursor.line + 1, 0, rest);
      cursor.line++;
      cursor.col = 0;
      clearSelection(selection);
      onChange();
      return;
    }
    if (e.key.length === 1) {
      e.preventDefault();
      if (hasSelection(selection)) deleteSelection(buffer, cursor, selection);
      const line = buffer[cursor.line];
      buffer[cursor.line] = line.slice(0, cursor.col) + e.key + line.slice(cursor.col);
      cursor.col++;
      clearSelection(selection);
      onChange();
    }
  });
}