import type {
  CommandDefaultsConfig,
  CommandTargetConfig,
  DefaultsConfig,
  HttpDefaultsConfig,
  HttpExpectConfig,
  HttpTargetConfig,
  ProbeConfig,
  ResolvedCommandTarget,
  ResolvedHttpTarget,
  ResolvedTarget,
  RuntimeConfig,
  TargetConfig,
  TargetType,
} from "./types";
import { parseSize } from "./size";
import { resolve } from "node:path";
import { dirname } from "node:path";

const DEFAULT_HOST = "127.0.0.1";
const DEFAULT_PORT = 3000;
const DEFAULT_DATA_DIR = "./data";
const DEFAULT_INTERVAL = "30s";
const DEFAULT_TIMEOUT = "10s";
const DEFAULT_HTTP_METHOD = "GET";
const DEFAULT_MAX_BODY_BYTES = "100MB";
const DEFAULT_MAX_OUTPUT_BYTES = "100MB";
const DEFAULT_MAX_CONCURRENT_CHECKS = 20;
const SUPPORTED_TYPES: TargetType[] = ["http", "command"];

export interface ResolvedConfig {
  host: string;
  port: number;
  dataDir: string;
  configDir: string;
  maxConcurrentChecks: number;
  targets: ResolvedTarget[];
}

export async function loadConfig(configPath: string): Promise<ResolvedConfig> {
  const file = Bun.file(configPath);

  if (!(await file.exists())) {
    throw new Error(`配置文件不存在: ${configPath}`);
  }

  const content = await file.text();
  const raw = Bun.YAML.parse(content) as ProbeConfig | null;

  if (!raw) {
    throw new Error("配置文件内容为空或格式无效");
  }

  validateConfig(raw);

  const configDir = dirname(resolve(configPath));
  const server = raw.server ?? {};
  const runtime = raw.runtime ?? {};
  const defaults = raw.defaults ?? {};

  const host = server.host ?? DEFAULT_HOST;
  const port = server.port ?? DEFAULT_PORT;
  const dataDir = server.dataDir ?? DEFAULT_DATA_DIR;

  if (!Number.isInteger(port) || port < 0 || port > 65535) {
    throw new Error(`无效端口号: ${port}，需要 0-65535 之间的整数`);
  }

  const maxConcurrentChecks = validateRuntime(runtime);
  const defaultIntervalMs = parseDuration(defaults.interval ?? DEFAULT_INTERVAL);
  const defaultTimeoutMs = parseDuration(defaults.timeout ?? DEFAULT_TIMEOUT);

  const targets: ResolvedTarget[] = raw.targets.map((target) =>
    resolveTarget(target, defaults, defaultIntervalMs, defaultTimeoutMs, configDir),
  );

  return { host, port, dataDir, configDir, maxConcurrentChecks, targets };
}

function validateRuntime(runtime: RuntimeConfig): number {
  if (runtime.maxConcurrentChecks === undefined) return DEFAULT_MAX_CONCURRENT_CHECKS;

  if (
    typeof runtime.maxConcurrentChecks !== "number" ||
    !Number.isInteger(runtime.maxConcurrentChecks) ||
    runtime.maxConcurrentChecks <= 0
  ) {
    throw new Error("runtime.maxConcurrentChecks 必须为正整数");
  }

  return runtime.maxConcurrentChecks;
}

function resolveTarget(
  target: TargetConfig,
  defaults: DefaultsConfig,
  defaultIntervalMs: number,
  defaultTimeoutMs: number,
  configDir: string,
): ResolvedTarget {
  const intervalMs = parseDuration(target.interval ?? defaults.interval ?? DEFAULT_INTERVAL);
  const timeoutMs = parseDuration(target.timeout ?? defaults.timeout ?? DEFAULT_TIMEOUT);
  const group = target.group ?? "default";

  if (target.type === "http") {
    return resolveHttpTarget(target, defaults.http, intervalMs, timeoutMs, group);
  }

  return resolveCommandTarget(target, defaults.command, intervalMs, timeoutMs, configDir, group);
}

function resolveHttpTarget(
  target: TargetConfig & { type: "http"; http: HttpTargetConfig },
  httpDefaults: HttpDefaultsConfig | undefined,
  intervalMs: number,
  timeoutMs: number,
  group: string,
): ResolvedHttpTarget {
  const maxBodyBytes = parseSize(target.http.maxBodyBytes ?? httpDefaults?.maxBodyBytes ?? DEFAULT_MAX_BODY_BYTES);

  return {
    type: "http",
    name: target.name,
    group,
    http: {
      url: target.http.url,
      method: target.http.method ?? httpDefaults?.method ?? DEFAULT_HTTP_METHOD,
      headers: { ...(httpDefaults?.headers ?? {}), ...(target.http.headers ?? {}) },
      body: target.http.body,
      maxBodyBytes,
    },
    intervalMs,
    timeoutMs,
    expect: target.expect as HttpExpectConfig | undefined,
  };
}

function resolveCommandTarget(
  target: TargetConfig & { type: "command"; command: CommandTargetConfig },
  commandDefaults: CommandDefaultsConfig | undefined,
  intervalMs: number,
  timeoutMs: number,
  configDir: string,
  group: string,
): ResolvedCommandTarget {
  const cwd = target.command.cwd ?? commandDefaults?.cwd ?? ".";
  const resolvedCwd = resolve(configDir, cwd);

  const maxOutputBytes = parseSize(
    target.command.maxOutputBytes ?? commandDefaults?.maxOutputBytes ?? DEFAULT_MAX_OUTPUT_BYTES,
  );

  const env = { ...process.env, ...(target.command.env ?? {}) } as Record<string, string>;

  return {
    type: "command",
    name: target.name,
    group,
    command: {
      exec: target.command.exec,
      args: target.command.args ?? [],
      cwd: resolvedCwd,
      env,
      maxOutputBytes,
    },
    intervalMs,
    timeoutMs,
    expect: target.expect as import("./types").CommandExpectConfig | undefined,
  };
}

function validateConfig(config: ProbeConfig): void {
  if (!config.targets || !Array.isArray(config.targets) || config.targets.length === 0) {
    throw new Error("配置文件必须包含至少一个 target");
  }

  const names = new Set<string>();

  for (let i = 0; i < config.targets.length; i++) {
    const raw = config.targets[i] as unknown as Record<string, unknown>;

    const name = raw["name"];
    if (!name || typeof name !== "string" || (name as string).trim() === "") {
      throw new Error(`第 ${i + 1} 个 target 缺少 name 字段`);
    }

    const type = raw["type"];
    if (!type || typeof type !== "string") {
      throw new Error(`target "${name}" 缺少 type 字段`);
    }

    if (!SUPPORTED_TYPES.includes(type as TargetType)) {
      throw new Error(`target "${name}" 使用不支持的 type: "${type}"，支持: ${SUPPORTED_TYPES.join(", ")}`);
    }

    if (type === "http") {
      const http = raw["http"] as Record<string, unknown> | undefined;
      if (!http?.["url"] || typeof http["url"] !== "string" || (http["url"] as string).trim() === "") {
        throw new Error(`target "${name}" 缺少 http.url 字段`);
      }
    }

    if (type === "command") {
      const cmd = raw["command"] as Record<string, unknown> | undefined;
      if (!cmd?.["exec"] || typeof cmd["exec"] !== "string" || (cmd["exec"] as string).trim() === "") {
        throw new Error(`target "${name}" 缺少 command.exec 字段`);
      }
    }

    const group = raw["group"];
    if (group !== undefined && typeof group !== "string") {
      throw new Error(`target "${name}" 的 group 字段必须为字符串`);
    }

    if (names.has(name as string)) {
      throw new Error(`target name 重复: "${name}"`);
    }

    names.add(name as string);
  }
}

const DURATION_REGEX = /^(\d+(?:\.\d+)?)(ms|s|m)$/;

export function parseDuration(value: string): number {
  const match = DURATION_REGEX.exec(value);
  if (!match) {
    throw new Error(`无效的时长格式: "${value}"，支持格式如 "30s"、"5m"、"500ms"`);
  }

  const num = parseFloat(match[1]!);
  const unit = match[2]!;

  if (unit === "ms") return num;
  if (unit === "s") return num * 1000;
  return num * 60 * 1000;
}