/**
 * Interactive terminal theme loader.
 *
 * Validates theme JSON, resolves color variables, watches custom theme files, and exposes terminal styling helpers.
 */
import * as fs from "node:fs";
import { getCapabilities } from "@earendil-works/pi-tui";
import chalk from "chalk";
import { type Static, Type } from "typebox";
import { Compile } from "typebox/compile";
import type { SourceInfo } from "../../../sessions/source-info.js";
import { highlight, supportsLanguage } from "../../../utils/syntax-highlight.js";

// ============================================================================
// Types & Schema
// ============================================================================

const ColorValueSchema = Type.Union([
  Type.String(), // hex "#ff0000", var ref "primary", or empty ""
  Type.Integer({ minimum: 0, maximum: 255 }), // 256-color index
]);

type ColorValue = Static<typeof ColorValueSchema>;

const ThemeJsonSchema = Type.Object({
  $schema: Type.Optional(Type.String()),
  name: Type.String(),
  vars: Type.Optional(Type.Record(Type.String(), ColorValueSchema)),
  colors: Type.Object({
    // Core UI (10 colors)
    accent: ColorValueSchema,
    border: ColorValueSchema,
    borderAccent: ColorValueSchema,
    borderMuted: ColorValueSchema,
    success: ColorValueSchema,
    error: ColorValueSchema,
    warning: ColorValueSchema,
    muted: ColorValueSchema,
    dim: ColorValueSchema,
    text: ColorValueSchema,
    thinkingText: ColorValueSchema,
    // Backgrounds & Content Text (11 colors)
    selectedBg: ColorValueSchema,
    userMessageBg: ColorValueSchema,
    userMessageText: ColorValueSchema,
    customMessageBg: ColorValueSchema,
    customMessageText: ColorValueSchema,
    customMessageLabel: ColorValueSchema,
    toolPendingBg: ColorValueSchema,
    toolSuccessBg: ColorValueSchema,
    toolErrorBg: ColorValueSchema,
    toolTitle: ColorValueSchema,
    toolOutput: ColorValueSchema,
    // Markdown (10 colors)
    mdHeading: ColorValueSchema,
    mdLink: ColorValueSchema,
    mdLinkUrl: ColorValueSchema,
    mdCode: ColorValueSchema,
    mdCodeBlock: ColorValueSchema,
    mdCodeBlockBorder: ColorValueSchema,
    mdQuote: ColorValueSchema,
    mdQuoteBorder: ColorValueSchema,
    mdHr: ColorValueSchema,
    mdListBullet: ColorValueSchema,
    // Tool Diffs (3 colors)
    toolDiffAdded: ColorValueSchema,
    toolDiffRemoved: ColorValueSchema,
    toolDiffContext: ColorValueSchema,
    // Syntax Highlighting (9 colors)
    syntaxComment: ColorValueSchema,
    syntaxKeyword: ColorValueSchema,
    syntaxFunction: ColorValueSchema,
    syntaxVariable: ColorValueSchema,
    syntaxString: ColorValueSchema,
    syntaxNumber: ColorValueSchema,
    syntaxType: ColorValueSchema,
    syntaxOperator: ColorValueSchema,
    syntaxPunctuation: ColorValueSchema,
    // Thinking Level Borders (6 colors)
    thinkingOff: ColorValueSchema,
    thinkingMinimal: ColorValueSchema,
    thinkingLow: ColorValueSchema,
    thinkingMedium: ColorValueSchema,
    thinkingHigh: ColorValueSchema,
    thinkingXhigh: ColorValueSchema,
    // Bash Mode (1 color)
    bashMode: ColorValueSchema,
  }),
  export: Type.Optional(
    Type.Object({
      pageBg: Type.Optional(ColorValueSchema),
      cardBg: Type.Optional(ColorValueSchema),
      infoBg: Type.Optional(ColorValueSchema),
    }),
  ),
});

type ThemeJson = Static<typeof ThemeJsonSchema>;

const validateThemeJson = Compile(ThemeJsonSchema);

type ThemeColor =
  | "accent"
  | "border"
  | "borderAccent"
  | "borderMuted"
  | "success"
  | "error"
  | "warning"
  | "muted"
  | "dim"
  | "text"
  | "thinkingText"
  | "userMessageText"
  | "customMessageText"
  | "customMessageLabel"
  | "toolTitle"
  | "toolOutput"
  | "mdHeading"
  | "mdLink"
  | "mdLinkUrl"
  | "mdCode"
  | "mdCodeBlock"
  | "mdCodeBlockBorder"
  | "mdQuote"
  | "mdQuoteBorder"
  | "mdHr"
  | "mdListBullet"
  | "toolDiffAdded"
  | "toolDiffRemoved"
  | "toolDiffContext"
  | "syntaxComment"
  | "syntaxKeyword"
  | "syntaxFunction"
  | "syntaxVariable"
  | "syntaxString"
  | "syntaxNumber"
  | "syntaxType"
  | "syntaxOperator"
  | "syntaxPunctuation"
  | "thinkingOff"
  | "thinkingMinimal"
  | "thinkingLow"
  | "thinkingMedium"
  | "thinkingHigh"
  | "thinkingXhigh"
  | "bashMode";

type ThemeBg =
  | "selectedBg"
  | "userMessageBg"
  | "customMessageBg"
  | "toolPendingBg"
  | "toolSuccessBg"
  | "toolErrorBg";

type ColorMode = "truecolor" | "256color";

// ============================================================================
// Color Utilities
// ============================================================================

function hexToRgb(hex: string): { r: number; g: number; b: number } {
  const cleaned = hex.replace("#", "");
  if (cleaned.length !== 6) {
    throw new Error(`Invalid hex color: ${hex}`);
  }
  const r = Number.parseInt(cleaned.slice(0, 2), 16);
  const g = Number.parseInt(cleaned.slice(2, 4), 16);
  const b = Number.parseInt(cleaned.slice(4, 6), 16);
  if (Number.isNaN(r) || Number.isNaN(g) || Number.isNaN(b)) {
    throw new Error(`Invalid hex color: ${hex}`);
  }
  return { r, g, b };
}

// The 6x6x6 color cube channel values (indices 0-5)
const CUBE_VALUES = [0, 95, 135, 175, 215, 255];

// Grayscale ramp values (indices 232-255, 24 grays from 8 to 238)
const GRAY_VALUES = Array.from({ length: 24 }, (_, i) => 8 + i * 10);

function findClosestPaletteIndex(value: number, palette: readonly number[]): number {
  let minDist = Infinity;
  let minIdx = 0;
  for (const [i, paletteValue] of palette.entries()) {
    const dist = Math.abs(value - paletteValue);
    if (dist < minDist) {
      minDist = dist;
      minIdx = i;
    }
  }
  return minIdx;
}

function colorDistance(
  r1: number,
  g1: number,
  b1: number,
  r2: number,
  g2: number,
  b2: number,
): number {
  // Weighted Euclidean distance (human eye is more sensitive to green)
  const dr = r1 - r2;
  const dg = g1 - g2;
  const db = b1 - b2;
  return dr * dr * 0.299 + dg * dg * 0.587 + db * db * 0.114;
}

function rgbTo256(r: number, g: number, b: number): number {
  // Find closest color in the 6x6x6 cube
  const rIdx = findClosestPaletteIndex(r, CUBE_VALUES);
  const gIdx = findClosestPaletteIndex(g, CUBE_VALUES);
  const bIdx = findClosestPaletteIndex(b, CUBE_VALUES);
  const cubeR = CUBE_VALUES[rIdx];
  const cubeG = CUBE_VALUES[gIdx];
  const cubeB = CUBE_VALUES[bIdx];
  if (cubeR === undefined || cubeG === undefined || cubeB === undefined) {
    throw new Error("Invalid 256-color cube index");
  }
  const cubeIndex = 16 + 36 * rIdx + 6 * gIdx + bIdx;
  const cubeDist = colorDistance(r, g, b, cubeR, cubeG, cubeB);

  // Find closest grayscale
  const gray = Math.round(0.299 * r + 0.587 * g + 0.114 * b);
  const grayIdx = findClosestPaletteIndex(gray, GRAY_VALUES);
  const grayValue = GRAY_VALUES[grayIdx];
  if (grayValue === undefined) {
    throw new Error("Invalid 256-color grayscale index");
  }
  const grayIndex = 232 + grayIdx;
  const grayDist = colorDistance(r, g, b, grayValue, grayValue, grayValue);

  // Check if color has noticeable saturation (hue matters)
  // If max-min spread is significant, prefer cube to preserve tint
  const maxC = Math.max(r, g, b);
  const minC = Math.min(r, g, b);
  const spread = maxC - minC;

  // Only consider grayscale if color is nearly neutral (spread < 10)
  // AND grayscale is actually closer
  if (spread < 10 && grayDist < cubeDist) {
    return grayIndex;
  }

  return cubeIndex;
}

function hexTo256(hex: string): number {
  const { r, g, b } = hexToRgb(hex);
  return rgbTo256(r, g, b);
}

function colorAnsi(color: string | number, mode: ColorMode, layer: "fg" | "bg"): string {
  const code = layer === "fg" ? 38 : 48;
  if (color === "") {
    return layer === "fg" ? "\x1b[39m" : "\x1b[49m";
  }
  if (typeof color === "number") {
    return `\x1b[${code};5;${color}m`;
  }
  if (color.startsWith("#")) {
    if (mode === "truecolor") {
      const { r, g, b } = hexToRgb(color);
      return `\x1b[${code};2;${r};${g};${b}m`;
    }
    const index = hexTo256(color);
    return `\x1b[${code};5;${index}m`;
  }
  throw new Error(`Invalid color value: ${color}`);
}

function resolveVarRefs(
  value: ColorValue,
  vars: Record<string, ColorValue>,
  visited = new Set<string>(),
): string | number {
  if (typeof value === "number" || value === "" || value.startsWith("#")) {
    return value;
  }
  if (visited.has(value)) {
    throw new Error(`Circular variable reference detected: ${value}`);
  }
  if (!(value in vars)) {
    throw new Error(`Variable reference not found: ${value}`);
  }
  visited.add(value);
  const resolved = vars[value];
  if (resolved === undefined) {
    throw new Error(`Variable reference not found: ${value}`);
  }
  return resolveVarRefs(resolved, vars, visited);
}

function resolveThemeColors<T extends Record<string, ColorValue>>(
  colors: T,
  vars: Record<string, ColorValue> = {},
): Record<keyof T, string | number> {
  const resolved: Record<string, string | number> = {};
  for (const [key, value] of Object.entries(colors)) {
    resolved[key] = resolveVarRefs(value, vars);
  }
  return resolved as Record<keyof T, string | number>;
}

// ============================================================================
// Theme Class
// ============================================================================

// Keep formatting independent of overridable public ANSI getters.
function getThemeAnsi(colors: ReadonlyMap<string, string>, color: string, label: string): string {
  const ansi = colors.get(color);
  if (!ansi) {
    throw new Error(`Unknown theme ${label}: ${color}`);
  }
  return ansi;
}

export class Theme {
  readonly name?: string;
  readonly sourcePath?: string;
  sourceInfo?: SourceInfo;
  private fgColors: Map<ThemeColor, string>;
  private bgColors: Map<ThemeBg, string>;
  private mode: ColorMode;

  constructor(
    fgColors: Record<ThemeColor, string | number>,
    bgColors: Record<ThemeBg, string | number>,
    mode: ColorMode,
    options: { name?: string; sourcePath?: string; sourceInfo?: SourceInfo } = {},
  ) {
    this.name = options.name;
    this.sourcePath = options.sourcePath;
    this.sourceInfo = options.sourceInfo;
    this.mode = mode;
    this.fgColors = new Map();
    for (const [key, value] of Object.entries(fgColors) as [ThemeColor, string | number][]) {
      this.fgColors.set(key, colorAnsi(value, mode, "fg"));
    }
    this.bgColors = new Map();
    for (const [key, value] of Object.entries(bgColors) as [ThemeBg, string | number][]) {
      this.bgColors.set(key, colorAnsi(value, mode, "bg"));
    }
  }

  fg(color: ThemeColor, text: string): string {
    const ansi = getThemeAnsi(this.fgColors, color, "color");
    return `${ansi}${text}\x1b[39m`; // Reset only foreground color
  }

  bg(color: ThemeBg, text: string): string {
    const ansi = getThemeAnsi(this.bgColors, color, "background color");
    return `${ansi}${text}\x1b[49m`; // Reset only background color
  }

  bold(text: string): string {
    return chalk.bold(text);
  }

  italic(text: string): string {
    return chalk.italic(text);
  }

  underline(text: string): string {
    return chalk.underline(text);
  }

  inverse(text: string): string {
    return chalk.inverse(text);
  }

  strikethrough(text: string): string {
    return chalk.strikethrough(text);
  }

  getFgAnsi(color: ThemeColor): string {
    return getThemeAnsi(this.fgColors, color, "color");
  }

  getBgAnsi(color: ThemeBg): string {
    return getThemeAnsi(this.bgColors, color, "background color");
  }

  getColorMode(): ColorMode {
    return this.mode;
  }

  getThinkingBorderColor(
    level: "off" | "minimal" | "low" | "medium" | "high" | "xhigh",
  ): (str: string) => string {
    // Map thinking levels to dedicated theme colors
    switch (level) {
      case "off":
        return (str: string) => this.fg("thinkingOff", str);
      case "minimal":
        return (str: string) => this.fg("thinkingMinimal", str);
      case "low":
        return (str: string) => this.fg("thinkingLow", str);
      case "medium":
        return (str: string) => this.fg("thinkingMedium", str);
      case "high":
        return (str: string) => this.fg("thinkingHigh", str);
      case "xhigh":
        return (str: string) => this.fg("thinkingXhigh", str);
      default:
        return (str: string) => this.fg("thinkingOff", str);
    }
  }

  getBashModeBorderColor(): (str: string) => string {
    return (str: string) => this.fg("bashMode", str);
  }
}

// ============================================================================
// Theme Loading
// ============================================================================

function parseThemeJson(label: string, json: unknown): ThemeJson {
  if (!validateThemeJson.Check(json)) {
    const errors = Array.from(validateThemeJson.Errors(json));
    const missingColors = new Set<string>();
    const otherErrors: string[] = [];

    for (const error of errors) {
      if (error.keyword === "required" && error.instancePath === "/colors") {
        const requiredProperties = (error.params as { requiredProperties?: string[] })
          .requiredProperties;
        for (const requiredProperty of requiredProperties ?? []) {
          missingColors.add(requiredProperty);
        }
        continue;
      }

      const pathLocal = error.instancePath || "/";
      otherErrors.push(`  - ${pathLocal}: ${error.message}`);
    }

    let errorMessage = `Invalid theme "${label}":\n`;
    if (missingColors.size > 0) {
      errorMessage += "\nMissing required color tokens:\n";
      errorMessage += Array.from(missingColors)
        .toSorted()
        .map((color) => `  - ${color}`)
        .join("\n");
      errorMessage += '\n\nPlease add these colors to your theme\'s "colors" object.';
      errorMessage += "\nSee the built-in themes (dark.json, light.json) for reference values.";
    }
    if (otherErrors.length > 0) {
      errorMessage += `\n\nOther errors:\n${otherErrors.join("\n")}`;
    }

    throw new Error(errorMessage);
  }

  return json;
}

function parseThemeJsonContent(label: string, content: string): ThemeJson {
  let json: unknown;
  try {
    json = JSON.parse(content);
  } catch (error) {
    const message = error instanceof Error ? error.message : String(error);
    throw new Error(`Failed to parse theme ${label}: ${message}`, { cause: error });
  }
  return parseThemeJson(label, json);
}

function createTheme(themeJson: ThemeJson, mode?: ColorMode, sourcePath?: string): Theme {
  const colorMode = mode ?? (getCapabilities().trueColor ? "truecolor" : "256color");
  const resolvedColors = resolveThemeColors(themeJson.colors, themeJson.vars);
  const fgColors: Record<ThemeColor, string | number> = {} as Record<ThemeColor, string | number>;
  const bgColors: Record<ThemeBg, string | number> = {} as Record<ThemeBg, string | number>;
  const bgColorKeys: Set<string> = new Set([
    "selectedBg",
    "userMessageBg",
    "customMessageBg",
    "toolPendingBg",
    "toolSuccessBg",
    "toolErrorBg",
  ]);
  for (const [key, value] of Object.entries(resolvedColors)) {
    if (bgColorKeys.has(key)) {
      bgColors[key as ThemeBg] = value;
    } else {
      fgColors[key as ThemeColor] = value;
    }
  }
  return new Theme(fgColors, bgColors, colorMode, {
    name: themeJson.name,
    sourcePath,
  });
}

export function loadThemeFromPath(themePath: string, mode?: ColorMode): Theme {
  const content = fs.readFileSync(themePath, "utf-8");
  const themeJson = parseThemeJsonContent(themePath, content);
  return createTheme(themeJson, mode, themePath);
}

// ============================================================================
// Global Theme Instance
// ============================================================================

// Use globalThis to share theme across module loaders (tsx + jiti in dev mode)
const THEME_KEY = Symbol.for("openclaw:agent-theme");

// Export theme as a getter that reads from globalThis
// This ensures all module instances (tsx, jiti) see the same theme
export const interactiveAgentTheme: Theme = new Proxy({} as Theme, {
  get(_target, prop) {
    const t = (globalThis as Record<symbol, Theme>)[THEME_KEY];
    if (!t) {
      throw new Error("Theme not initialized. Call setTheme() first.");
    }
    return (t as unknown as Record<string | symbol, unknown>)[prop];
  },
});

// ============================================================================
// HTML Export Helpers
// ============================================================================

// ============================================================================
// TUI Helpers
// ============================================================================

type CliHighlightTheme = Record<string, (s: string) => string>;

let cachedHighlightThemeFor: Theme | undefined;
let cachedCliHighlightTheme: CliHighlightTheme | undefined;

function buildCliHighlightTheme(t: Theme): CliHighlightTheme {
  return {
    keyword: (s: string) => t.fg("syntaxKeyword", s),
    built_in: (s: string) => t.fg("syntaxType", s),
    literal: (s: string) => t.fg("syntaxNumber", s),
    number: (s: string) => t.fg("syntaxNumber", s),
    string: (s: string) => t.fg("syntaxString", s),
    comment: (s: string) => t.fg("syntaxComment", s),
    function: (s: string) => t.fg("syntaxFunction", s),
    title: (s: string) => t.fg("syntaxFunction", s),
    class: (s: string) => t.fg("syntaxType", s),
    type: (s: string) => t.fg("syntaxType", s),
    attr: (s: string) => t.fg("syntaxVariable", s),
    variable: (s: string) => t.fg("syntaxVariable", s),
    params: (s: string) => t.fg("syntaxVariable", s),
    operator: (s: string) => t.fg("syntaxOperator", s),
    punctuation: (s: string) => t.fg("syntaxPunctuation", s),
  };
}

function getCliHighlightTheme(t: Theme): CliHighlightTheme {
  if (cachedHighlightThemeFor !== t || !cachedCliHighlightTheme) {
    cachedHighlightThemeFor = t;
    cachedCliHighlightTheme = buildCliHighlightTheme(t);
  }
  return cachedCliHighlightTheme;
}

/**
 * Highlight code with syntax coloring based on file extension or language.
 * Returns array of highlighted lines.
 */
export function highlightCode(code: string, lang?: string): string[] {
  // Validate language before highlighting to avoid stderr spam from cli-highlight
  const validLang = lang && supportsLanguage(lang) ? lang : undefined;
  // Skip highlighting when no valid language is specified. cli-highlight's
  // auto-detection is unreliable and can misidentify prose as AppleScript,
  // LiveCodeServer, etc., coloring random English words as keywords.
  if (!validLang) {
    return code.split("\n").map((line) => interactiveAgentTheme.fg("mdCodeBlock", line));
  }
  const opts = {
    language: validLang,
    ignoreIllegals: true,
    theme: getCliHighlightTheme(interactiveAgentTheme),
  };
  try {
    return highlight(code, opts).split("\n");
  } catch {
    return code.split("\n");
  }
}

/**
 * Get language identifier from file path extension.
 */
export function getLanguageFromPath(filePath: string): string | undefined {
  const ext = filePath.split(".").pop()?.toLowerCase();
  if (!ext) {
    return undefined;
  }

  const extToLang: Record<string, string> = {
    ts: "typescript",
    tsx: "typescript",
    js: "javascript",
    jsx: "javascript",
    mjs: "javascript",
    cjs: "javascript",
    py: "python",
    rb: "ruby",
    rs: "rust",
    go: "go",
    java: "java",
    kt: "kotlin",
    swift: "swift",
    c: "c",
    h: "c",
    cpp: "cpp",
    cc: "cpp",
    cxx: "cpp",
    hpp: "cpp",
    cs: "csharp",
    php: "php",
    sh: "bash",
    bash: "bash",
    zsh: "bash",
    fish: "fish",
    ps1: "powershell",
    sql: "sql",
    html: "html",
    htm: "html",
    css: "css",
    scss: "scss",
    sass: "sass",
    less: "less",
    json: "json",
    yaml: "yaml",
    yml: "yaml",
    toml: "toml",
    xml: "xml",
    md: "markdown",
    markdown: "markdown",
    dockerfile: "dockerfile",
    makefile: "makefile",
    cmake: "cmake",
    lua: "lua",
    perl: "perl",
    r: "r",
    scala: "scala",
    clj: "clojure",
    ex: "elixir",
    exs: "elixir",
    erl: "erlang",
    hs: "haskell",
    ml: "ocaml",
    vim: "vim",
    graphql: "graphql",
    proto: "protobuf",
    tf: "hcl",
    hcl: "hcl",
  };

  return extToLang[ext];
}