import { z } from "zod";
import { createHash } from "node:crypto";
import type { JSONSchema7 } from "json-schema";
import type { ToolExecutor, ToolContext, ToolResult } from "../../registry";
import type { HashToolConfig } from "./config";

export const hashInputSchema = z.object({
  operation: z
    .enum(["hash", "compare"])
    .describe("操作类型: hash=计算哈希, compare=比较哈希值"),
  text: z
    .string()
    .min(1)
    .max(100000)
    .describe("要计算哈希的文本内容"),
  algorithm: z
    .enum(["md5", "sha1", "sha256", "sha512"])
    .optional()
    .describe("哈希算法，不传则使用配置默认值"),
  expectedHash: z
    .string()
    .optional()
    .describe("compare 操作时，要对比的期望哈希值"),
});

type HashInput = z.infer<typeof hashInputSchema>;

function computeHash(text: string, algorithm: string, uppercase: boolean): string {
  const hash = createHash(algorithm).update(text, "utf8").digest("hex");
  return uppercase ? hash.toUpperCase() : hash;
}

export const hashExecutor: ToolExecutor<HashToolConfig> = {
  buildInputSchema(_config: HashToolConfig): JSONSchema7 {
    return {
      type: "object",
      properties: {
        operation: {
          type: "string",
          enum: ["hash", "compare"],
          description: "操作类型: hash=计算哈希, compare=比较哈希值",
        },
        text: { type: "string", description: "要计算哈希的文本内容" },
        algorithm: {
          type: "string",
          enum: ["md5", "sha1", "sha256", "sha512"],
          description: "哈希算法",
        },
        expectedHash: { type: "string", description: "compare 操作的期望哈希值" },
      },
      required: ["operation", "text"],
    };
  },

  buildDescription(config: HashToolConfig): string {
    return `哈希计算工具。支持 md5、sha1、sha256、sha512 算法。可计算文本哈希值或对比哈希是否匹配。默认算法: ${config.defaultAlgorithm}，输出${config.uppercase ? "大写" : "小写"}。`;
  },

  async execute(
    input: unknown,
    config: HashToolConfig,
    _ctx: ToolContext,
  ): Promise<ToolResult> {
    const start = Date.now();

    const parsed = hashInputSchema.safeParse(input);
    if (!parsed.success) {
      return {
        success: false,
        data: null,
        error: `输入参数校验失败: ${parsed.error.message}`,
        metadata: { durationMs: Date.now() - start },
      };
    }

    const inp = parsed.data as HashInput;
    const algorithm = inp.algorithm ?? config.defaultAlgorithm;

    try {
      switch (inp.operation) {
        case "hash": {
          const hashValue = computeHash(inp.text, algorithm, config.uppercase);
          return {
            success: true,
            data: {
              algorithm,
              inputLength: inp.text.length,
              hash: hashValue,
            },
            metadata: { durationMs: Date.now() - start },
          };
        }

        case "compare": {
          if (!inp.expectedHash) {
            throw new Error("compare 操作需要 expectedHash 参数");
          }
          const actualHash = computeHash(inp.text, algorithm, config.uppercase);
          const expected = config.uppercase
            ? inp.expectedHash.toUpperCase()
            : inp.expectedHash.toLowerCase();
          const matched = actualHash === expected;
          return {
            success: true,
            data: {
              algorithm,
              matched,
              actualHash,
              expectedHash: expected,
            },
            metadata: { durationMs: Date.now() - start },
          };
        }

        default:
          throw new Error(`未知操作: ${inp.operation}`);
      }
    } catch (e) {
      return {
        success: false,
        data: null,
        error: e instanceof Error ? e.message : String(e),
        metadata: { durationMs: Date.now() - start },
      };
    }
  },
};