// 配置加载与持久化
// 配置文件位置：~/.pi/agent/ccline/config.json（主题/段/style）
// 模型映射：  ~/.pi/agent/ccline/models.json（可选，覆盖默认 ModelConfig）

import { existsSync, mkdirSync, readFileSync, writeFileSync } from "node:fs";
import { join } from "node:path";
import { getAgentDir } from "@earendil-works/pi-coding-agent";
import type { Config, ModelConfig, SegmentId } from "./types.ts";
import { getTheme, defaultThemeName } from "./themes.ts";

const DIR = "ccline";

/** 配置版本：
 *  1 = 初版（thinking/tokens/cost 默认关闭）
 *  2 = 新增 cache/session 段（tokens/cache/cost 曾一度默认显示）
 *  3 = 默认只保留 Model/Thinking/Directory/Git/Context Window，tokens/cache/cost 改回默认关闭 */
export const CONFIG_VERSION = 3;

/** 各版本段的默认启用状态（逐版本迁移时用于识别“用户未改过”的段） */
const VERSION_ENABLED: Record<number, Partial<Record<SegmentId, boolean>>> = {
  1: {
    model: true,
    directory: true,
    git: true,
    contextWindow: true,
    tokens: false,
    cost: false,
    thinking: false,
  },
  2: {
    model: true,
    thinking: true,
    directory: true,
    git: true,
    session: false,
    contextWindow: true,
    tokens: true,
    cache: true,
    cost: true,
  },
  3: {
    model: true,
    thinking: true,
    directory: true,
    git: true,
    session: false,
    contextWindow: true,
    tokens: false,
    cache: false,
    cost: false,
  },
};

function cclineDir(): string {
  // ~/.pi/agent/ccline
  return join(getAgentDir(), DIR);
}
function configPath(): string {
  return join(cclineDir(), "config.json");
}
function modelsPath(): string {
  return join(cclineDir(), "models.json");
}

/** 默认 ModelConfig（移植 CCometixLine 默认第三方模型 + 1M 修饰符） */
export function defaultModelConfig(): ModelConfig {
  return {
    models: [
      { pattern: "glm-4.5", displayName: "GLM-4.5", contextLimit: 128_000 },
      { pattern: "kimi-k2-turbo", displayName: "Kimi K2 Turbo", contextLimit: 128_000 },
      { pattern: "kimi-k2", displayName: "Kimi K2", contextLimit: 128_000 },
      { pattern: "qwen3-coder", displayName: "Qwen Coder", contextLimit: 256_000 },
    ],
    contextModifiers: [{ pattern: "[1m]", displaySuffix: " 1M", contextLimit: 1_000_000 }],
  };
}

/** 合并用户原始段配置（校验 id/enabled 等基本字段） */
function normalizeSegments(raw: unknown): Config["segments"] | undefined {
  if (!Array.isArray(raw) || raw.length === 0) return undefined;
  const result: Config["segments"] = [];
  for (const s of raw) {
    if (!s || typeof s !== "object" || typeof s.id !== "string") continue;
    result.push({
      id: s.id as Config["segments"][number]["id"],
      enabled: s.enabled !== false,
      icon: {
        plain: s.icon?.plain ?? "",
        nerdFont: s.icon?.nerdFont ?? "",
      },
      colors: {
        icon: s.colors?.icon,
        text: s.colors?.text,
        background: s.colors?.background,
      },
      styles: { textBold: s.styles?.textBold === true },
      options: s.options ?? {},
    });
  }
  return result;
}

/** 合并配置中的段与主题预设：已有段保留用户配置，缺失的新增段按主题规范顺序补齐 */
function mergeSegments(saved: Config["segments"], defaults: Config["segments"]): Config["segments"] {
  const savedById = new Map(saved.map((s) => [s.id, s]));
  const hasMissing = defaults.some((d) => !savedById.has(d.id));
  if (!hasMissing) return saved;
  return defaults.map((d) => savedById.get(d.id) ?? d);
}

/** 逐版本套用默认值：仅当段的启用状态仍等于上一版默认值时，才更新为本版默认值 */
function migrateConfig(config: Config, fromVersion: number): Config {
  let segments = config.segments;
  for (let v = fromVersion; v < CONFIG_VERSION; v++) {
    const prev = VERSION_ENABLED[v];
    const next = VERSION_ENABLED[v + 1];
    if (!prev || !next) continue;
    segments = segments.map((s) => {
      const p = prev[s.id];
      const n = next[s.id];
      if (p === undefined || n === undefined || s.enabled !== p) return s;
      return { ...s, enabled: n };
    });
  }
  return { ...config, segments };
}

/** 检测旧版 4 位 \uXXXX 转义残留的坏 NerdFont 图标
 *  旧 bug：themes.ts 写 "\uf024b"，JS 解析为 U+F024 + 字面 'b'，
 *  saveConfig 存盘后 icon.nerdFont 变成 2 字符（PUA + ASCII 字母/数字）。
 *  合法 NerdFont 图标都是单个 PUA codepoint，不会是 PUA+ASCII 组合。 */
function isCorruptNerdIcon(nf: string): boolean {
  const chars = Array.from(nf);
  if (chars.length !== 2) return false;
  const cp0 = chars[0].codePointAt(0) ?? 0;
  const cp1 = chars[1].codePointAt(0) ?? 0;
  const isPUA = (cp0 >= 0xe000 && cp0 <= 0xf8ff) || (cp0 >= 0xf0000 && cp0 <= 0xffffd);
  const isAsciiVisible = cp1 >= 0x21 && cp1 <= 0x7e;
  return isPUA && isAsciiVisible;
}

/** Nerd Fonts v3 已移除的旧版图标码点（命中则回退到当前主题默认图标） */
const STALE_NERD_ICONS = new Set([
  "\u{f5dc}", // Nerd Fonts v2 时代的 MDI brain 码点，v3 已移除
]);

/** 迁移段配置：修正坏/失效的 NerdFont 图标 + 补 contextWindow plain emoji 的 VS16，返回新 config 与是否变化 */
function migrateSegments(config: Config): { config: Config; changed: boolean } {
  const defaults = getTheme(config.theme);
  const defById = new Map(defaults.segments.map((s) => [s.id, s]));
  let anyChanged = false;
  const segments = config.segments.map((s) => {
    const def = defById.get(s.id);
    if (!def) return s;
    let plain = s.icon.plain;
    let nerdFont = s.icon.nerdFont;
    let segChanged = false;
    if ((isCorruptNerdIcon(nerdFont) || STALE_NERD_ICONS.has(nerdFont)) && def.icon.nerdFont !== nerdFont) {
      nerdFont = def.icon.nerdFont; // 用当前主题默认图标修正
      segChanged = true;
    }
    if (s.id === "contextWindow" && plain === "⚡") {
      plain = "⚡️"; // 补 VS16 emoji 选择符，对齐 CCometixLine
      segChanged = true;
    }
    if (!segChanged) return s;
    anyChanged = true;
    return { ...s, icon: { plain, nerdFont } };
  });
  return { config: { ...config, segments }, changed: anyChanged };
}

/** 加载完整配置：config.json 覆盖主题预设；models.json 覆盖默认 ModelConfig */
export function loadConfig(): { config: Config; modelConfig: ModelConfig; enabled: boolean } {
  let config: Config = getTheme(defaultThemeName());
  let modelConfig: ModelConfig = defaultModelConfig();
  let enabled = true;
  let needsSave = false;

  // 1. config.json
  try {
    if (existsSync(configPath())) {
      const raw = JSON.parse(readFileSync(configPath(), "utf8"));
      if (typeof raw.theme === "string") config = getTheme(raw.theme);
      if (raw.style) config = { ...config, style: { ...config.style, ...raw.style } };
      const segs = normalizeSegments(raw.segments);
      if (segs) config = { ...config, segments: mergeSegments(segs, config.segments) };
      if (raw.models) modelConfig = { ...modelConfig, ...raw.models };
      if (raw.enabled === false) enabled = false; // 总开关

      // 版本迁移：逐版本补齐新增段并对齐新默认值
      const version = typeof raw.version === "number" ? raw.version : 1;
      if (version < CONFIG_VERSION) {
        config = { ...migrateConfig(config, version), version: CONFIG_VERSION };
        needsSave = true;
      }
    }
  } catch {
    // 损坏的配置文件忽略，使用默认
  }

  // 迁移：修正旧版 4 位 \uXXXX 转义残留的坏 NerdFont 图标，固化写回避免每次迁移
  const migrated = migrateSegments(config);
  if (migrated.changed) {
    config = migrated.config;
    needsSave = true;
  }
  if (needsSave) saveConfig(config, enabled);

  // 2. models.json（优先级更高，独立文件便于单独维护）
  try {
    if (existsSync(modelsPath())) {
      const m = JSON.parse(readFileSync(modelsPath(), "utf8"));
      modelConfig = { ...modelConfig, ...m };
    }
  } catch {
    // 忽略
  }

  return { config, modelConfig, enabled };
}

/** 保存配置（主题/段/style，可选 enabled 总开关） */
export function saveConfig(config: Config, enabled?: boolean): void {
  try {
    mkdirSync(cclineDir(), { recursive: true });
    const payload =
      enabled === undefined
        ? { ...config, version: CONFIG_VERSION }
        : { ...config, version: CONFIG_VERSION, enabled };
    writeFileSync(configPath(), JSON.stringify(payload, null, 2), "utf8");
  } catch {
    // 忽略写入错误
  }
}

/** 保存模型映射 */
export function saveModelConfig(mc: ModelConfig): void {
  try {
    mkdirSync(cclineDir(), { recursive: true });
    writeFileSync(modelsPath(), JSON.stringify(mc, null, 2), "utf8");
  } catch {
    // 忽略
  }
}

/** 初始化默认配置文件（若不存在） */
export function initConfig(): void {
  try {
    mkdirSync(cclineDir(), { recursive: true });
  } catch {
    // 忽略
  }
  if (!existsSync(configPath())) saveConfig(getTheme(defaultThemeName()));
  if (!existsSync(modelsPath())) saveModelConfig(defaultModelConfig());
}