import { readFile, readdir } from 'node:fs/promises';
import path from 'node:path';
import {
  type CodingSkillId,
} from '../../shared/coding-skills';
import type {
  ProductCodingCommand,
  ProductCodingSkill,
  ProductPiCommandInput,
} from '../../shared/coding-product-tools';

export type {
  ProductCodingCommand,
  ProductCodingSkill,
  ProductPiCommandInput,
} from '../../shared/coding-product-tools';

const MAKELORE_COMMANDS: readonly ProductCodingCommand[] = [
  { name: 'models', title: '切换模型', description: '切换当前会话后续轮次使用的模型', source: 'makelore' },
  { name: 'thinking', title: '思考强度', description: '设置当前会话的思考强度', source: 'makelore' },
  { name: 'compact', title: '压缩会话', description: '使用当前模型总结会话上下文', source: 'makelore' },
  { name: 'fork', title: '分叉会话', description: '从当前用户消息创建新的产品会话', source: 'makelore' },
  { name: 'recover', title: '恢复会话', description: '重新创建当前会话 worker 并恢复状态', source: 'makelore' },
] as const;

const COMMAND_NAME_PATTERN = /^[A-Za-z0-9][A-Za-z0-9._:-]{0,63}$/;

export interface ProductCodingPluginSkillSource {
  id: string;
  pluginId?: string;
  directory: string;
  available?: boolean;
  /** Package-relative Skill entry; defaults to `SKILL.md`. */
  entryPath?: string;
}

function frontmatterScalar(content: string, key: string): string | undefined {
  const block = content.match(/^---\s*\r?\n([\s\S]*?)\r?\n---(?:\r?\n|$)/)?.[1];
  if (!block) return undefined;
  const line = block.split(/\r?\n/).find((candidate) => candidate.startsWith(`${key}:`));
  if (!line) return undefined;
  const value = line.slice(key.length + 1).trim();
  if ((value.startsWith('"') && value.endsWith('"'))
    || (value.startsWith("'") && value.endsWith("'"))) {
    return value.slice(1, -1).trim() || undefined;
  }
  return value || undefined;
}

function selectedSkillIds(
  value: readonly string[],
  allIds: readonly string[],
): Set<string> {
  const allowed = new Set<string>(allIds);
  const selected = new Set<string>();
  for (const raw of value) {
    const id = raw.trim();
    // Old project assignments are retained in project.json, but a removed or
    // not-yet-installed provider must not break the current capability list.
    if (allowed.has(id)) selected.add(id);
  }
  return selected;
}

function productSkillId(id: string): CodingSkillId {
  return id;
}

async function listSkillEntries(
  directory: string,
  relative = '',
): Promise<Array<{ path: string; type: 'file' | 'directory' }>> {
  const entries = await readdir(path.join(directory, relative), { withFileTypes: true });
  const result: Array<{ path: string; type: 'file' | 'directory' }> = [];
  for (const entry of entries.sort((left, right) => left.name.localeCompare(right.name))) {
    const entryPath = relative ? path.posix.join(relative, entry.name) : entry.name;
    if (entry.isDirectory()) {
      result.push({ path: entryPath, type: 'directory' });
      result.push(...await listSkillEntries(directory, entryPath));
    } else if (entry.isFile()) {
      result.push({ path: entryPath, type: 'file' });
    }
  }
  return result;
}

export async function listProductCodingSkills(
  _bundledSkillsDir: string,
  selectedIds: readonly string[] = [],
  pluginSkillSources: readonly ProductCodingPluginSkillSource[] = [],
): Promise<ProductCodingSkill[]> {
  const pluginIds = pluginSkillSources.map(({ id }) => id);
  const allIds = [...pluginIds];
  if (new Set(allIds).size !== allIds.length) {
    throw new Error('Duplicate coding skill identifier');
  }
  const selected = selectedSkillIds(selectedIds, allIds);
  const sources: ProductCodingPluginSkillSource[] = [...pluginSkillSources];
  const visibleSources = sources.filter(({ id, available }) => available !== false || selected.has(id));
  return await Promise.all(visibleSources.map(async ({ id, directory, entryPath, available = true }) => {
    const sourceLocation = path.resolve(directory);
    const location = sourceLocation;
    const content = await readFile(path.join(sourceLocation, entryPath ?? 'SKILL.md'), 'utf8');
    return {
      id: productSkillId(id),
      name: frontmatterScalar(content, 'name') ?? id,
      description: frontmatterScalar(content, 'description') ?? '',
      selected: selected.has(id),
      available,
      effective: available && selected.has(id),
      location,
      content,
      entries: await listSkillEntries(sourceLocation),
    };
  }));
}

export function buildProductCodingCommandCatalog(
  skills: readonly ProductCodingSkill[],
  piCommands: readonly ProductPiCommandInput[] = [],
): ProductCodingCommand[] {
  const commands = [...MAKELORE_COMMANDS];
  const used = new Set(commands.map((command) => command.name.toLocaleLowerCase()));
  for (const command of piCommands) {
    const name = command.name.trim();
    const key = name.toLocaleLowerCase();
    if (!COMMAND_NAME_PATTERN.test(name) || used.has(key)) continue;
    used.add(key);
    commands.push({
      name,
      title: name,
      description: command.description?.trim() || 'Pi 命令',
      source: 'pi',
    });
  }
  for (const skill of skills) {
    const key = skill.id.toLocaleLowerCase();
    if (!skill.effective || used.has(key)) continue;
    used.add(key);
    commands.push({
      name: skill.id,
      title: skill.name,
      description: skill.description || '项目技能',
      source: 'skill',
      skillId: skill.id,
    });
  }
  return commands;
}