/**
 * Custom ANSI selectors with live preview support.
 * The tree IS the selector — arrow keys navigate, right panel updates live.
 *
 * @module
 */

import chalk from "chalk";

export interface ISelectOption {
  label: string;
  value: string;
  hint?: string;
}

// ─── Theme ───────────────────────────────────────────────────────────────────

const T = {
  accent: "#a875ff",     // brighter purple for bullets
  selectedBg: "#2d1f5e", // visible bg even on dark terminals
  selectedFg: "#ffffff",  // white text on selected
  normal: "#cccccc",      // normal unselected labels (high contrast)
  dim: "#888888",         // dimmed unselected labels
  hint: "#999999",        // hints next to labels
  sep: "#444444",         // separator lines
};

// ─── Dual-panel select (tree left + preview right) ───────────────────────────

/**
 * Interactive selector rendered at a position, with a callback on each
 * highlight change so the caller can update a right-side preview panel.
 *
 * @param options - Selectable items
 * @param startRow - Terminal row (1-based) where the selector starts
 * @param startCol - Terminal column (1-based) where the selector starts
 * @param onHighlight - Called on each arrow key move with the highlighted value.
 *                      Use this to re-render a detail panel to the right.
 * @returns Selected value on Enter, null on Esc/Ctrl+C
 */
export function inlineSelect(
  options: ISelectOption[],
  startRow: number,
  startCol: number,
  onHighlight?: (value: string, index: number) => void,
): Promise<string | null> {
  let selected = 0;
  // Skip separators
  while (selected < options.length && (!options[selected].value || options[selected].value === "_sep")) selected++;

  function render(clearExtra = false): void {
    for (let i = 0; i < options.length; i++) {
      process.stdout.write(`\x1b[${startRow + i};${startCol}H\x1b[K`);
      process.stdout.write(formatItem(options[i], i === selected));
    }
    // Clear leftover lines from previous menus (up to 15 extra lines)
    if (clearExtra) {
      for (let i = 0; i < 15; i++) {
        process.stdout.write(`\x1b[${startRow + options.length + i};${startCol}H\x1b[K`);
      }
    }
  }

  return new Promise((resolve) => {
    if (!process.stdin.isTTY) { resolve(null); return; }

    process.stdout.write("\x1b[?25l"); // hide cursor
    const wasRaw = process.stdin.isRaw;
    process.stdin.setRawMode(true);
    process.stdin.resume();
    process.stdin.setEncoding("utf8");

    render(true); // First render clears leftover lines from previous menus
    onHighlight?.(options[selected].value, selected);

    const onData = (key: string): void => {
      if (key === "\x1b[A" || key === "k") { // Up
        do { selected = (selected - 1 + options.length) % options.length; }
        while (!options[selected].value || options[selected].value === "_sep");
        render();
        onHighlight?.(options[selected].value, selected);
        return;
      }
      if (key === "\x1b[B" || key === "j") { // Down
        do { selected = (selected + 1) % options.length; }
        while (!options[selected].value || options[selected].value === "_sep");
        render();
        onHighlight?.(options[selected].value, selected);
        return;
      }
      if (key.charCodeAt(0) === 13) { cleanup(); resolve(options[selected].value); return; } // Enter
      if ((key.charCodeAt(0) === 27 && key.length === 1) || key === "q") { cleanup(); resolve(null); return; } // Esc
      if (key.charCodeAt(0) === 3) { cleanup(); resolve(null); return; } // Ctrl+C
    };

    function cleanup(): void {
      process.stdin.removeListener("data", onData);
      process.stdin.setRawMode(wasRaw ?? false);
      process.stdin.pause();
      process.stdout.write("\x1b[?25h");
      process.stdout.write(`\x1b[${startRow + options.length + 1};1H`);
    }

    process.stdin.on("data", onData);
  });
}

// ─── Full-width select (below current output) ───────────────────────────────

/**
 * Full-width selector below current output. For sub-menus (actions, logs, env).
 */
export async function fullSelect(
  title: string,
  options: ISelectOption[],
  onHighlight?: (value: string, index: number, startRow: number) => void,
): Promise<string | null> {
  let selected = 0;
  while (selected < options.length && (!options[selected].value || options[selected].value === "_sep")) selected++;

  // Print title + reserve space for options
  if (title) console.log(`\n  ${chalk.bold(title)}`);

  // Use CSI 6n to get actual cursor row BEFORE printing option lines
  const cursorRowBefore = await getCursorRowAsync();
  const optionsStartRow = cursorRowBefore;

  // Reserve vertical space
  for (let i = 0; i < options.length; i++) process.stdout.write("\n");

  function render(): void {
    // Use absolute row positioning to avoid drift
    for (let i = 0; i < options.length; i++) {
      process.stdout.write(`\x1b[${optionsStartRow + i};4H\x1b[K`);
      process.stdout.write(formatItem(options[i], i === selected));
    }
    // Park cursor after the list
    process.stdout.write(`\x1b[${optionsStartRow + options.length};1H`);
  }

  return new Promise((resolve) => {
    if (!process.stdin.isTTY) { resolve(null); return; }

    process.stdout.write("\x1b[?25l");
    const wasRaw = process.stdin.isRaw;
    process.stdin.setRawMode(true);
    process.stdin.resume();
    process.stdin.setEncoding("utf8");

    render();
    onHighlight?.(options[selected].value, selected, optionsStartRow);

    const onData = (key: string): void => {
      if (key === "\x1b[A" || key === "k") {
        do { selected = (selected - 1 + options.length) % options.length; }
        while (!options[selected].value || options[selected].value === "_sep");
        render(); onHighlight?.(options[selected].value, selected, optionsStartRow); return;
      }
      if (key === "\x1b[B" || key === "j") {
        do { selected = (selected + 1) % options.length; }
        while (!options[selected].value || options[selected].value === "_sep");
        render(); onHighlight?.(options[selected].value, selected, optionsStartRow); return;
      }
      if (key.charCodeAt(0) === 13) { cleanup(); resolve(options[selected].value); return; }
      if ((key.charCodeAt(0) === 27 && key.length === 1) || key === "q") { cleanup(); resolve(null); return; }
      if (key.charCodeAt(0) === 3) { cleanup(); resolve(null); return; }
    };

    function cleanup(): void {
      process.stdin.removeListener("data", onData);
      process.stdin.setRawMode(wasRaw ?? false);
      process.stdin.pause();
      process.stdout.write("\x1b[?25h");
    }

    process.stdin.on("data", onData);
  });
}

// ─── Text input ──────────────────────────────────────────────────────────────

export function textInput(message: string): Promise<string | null> {
  return new Promise((resolve) => {
    if (!process.stdin.isTTY) { resolve(null); return; }
    process.stdout.write(`\n  ${chalk.hex(T.accent)("?")} ${chalk.bold(message)} `);
    process.stdin.setRawMode(false);
    process.stdin.resume();
    process.stdin.setEncoding("utf8");
    const onData = (data: string): void => {
      process.stdin.removeListener("data", onData);
      process.stdin.pause();
      resolve(data.trim() || null);
    };
    process.stdin.on("data", onData);
  });
}

export function confirm(message: string): Promise<boolean | null> {
  return new Promise((resolve) => {
    if (!process.stdin.isTTY) { resolve(null); return; }
    process.stdout.write(`\n  ${chalk.hex(T.accent)("?")} ${chalk.bold(message)} ${chalk.gray("(y/n)")} `);
    const wasRaw = process.stdin.isRaw;
    process.stdin.setRawMode(true);
    process.stdin.resume();
    process.stdin.setEncoding("utf8");
    const onData = (key: string): void => {
      process.stdin.removeListener("data", onData);
      process.stdin.setRawMode(wasRaw ?? false);
      process.stdin.pause();
      process.stdout.write("\n");
      if (key === "y" || key === "Y") resolve(true);
      else if (key.charCodeAt(0) === 3 || key.charCodeAt(0) === 27) resolve(null);
      else resolve(false);
    };
    process.stdin.on("data", onData);
  });
}

// ─── Formatting ──────────────────────────────────────────────────────────────

function formatItem(opt: ISelectOption, isSelected: boolean): string {
  if (!opt.value || opt.value === "_sep") {
    return chalk.hex(T.sep)("  ───────────────────");
  }

  if (isSelected) {
    const bullet = chalk.hex(T.accent)("▸ ");
    const label = chalk.bgHex(T.selectedBg).hex(T.selectedFg).bold(` ${opt.label} `);
    // Don't wrap hint in a color — it may contain pre-colored text (●, ✗)
    const hint = opt.hint ? ` ${opt.hint}` : "";
    return `${bullet}${label}${hint}`;
  }

  const bullet = chalk.hex(T.dim)("  ");
  const label = chalk.hex(T.normal)(opt.label);
  // Hints on unselected items: pass through (may have colors)
  const hint = opt.hint ? ` ${opt.hint}` : "";
  return `${bullet}${label}${hint}`;
}

// ─── Cursor position query ───────────────────────────────────────────────────

/**
 * Get the current cursor row using CSI 6n (Device Status Report).
 * Falls back to a reasonable guess if the terminal doesn't respond.
 */
function getCursorRowAsync(): Promise<number> {
  return new Promise((resolve) => {
    if (!process.stdout.isTTY || !process.stdin.isTTY) {
      resolve(10);
      return;
    }

    const timeout = setTimeout(() => {
      process.stdin.removeListener("data", onData);
      process.stdin.setRawMode(wasRaw ?? false);
      process.stdin.pause();
      resolve(10); // fallback
    }, 150);

    const wasRaw = process.stdin.isRaw;
    process.stdin.setRawMode(true);
    process.stdin.resume();
    process.stdin.setEncoding("utf8");

    const onData = (data: string): void => {
      const match = data.match(/\x1b\[(\d+);(\d+)R/);
      if (match) {
        clearTimeout(timeout);
        process.stdin.removeListener("data", onData);
        process.stdin.setRawMode(wasRaw ?? false);
        process.stdin.pause();
        resolve(parseInt(match[1], 10));
      }
    };

    process.stdin.on("data", onData);
    process.stdout.write("\x1b[6n"); // Query cursor position
  });
}