import { promises as fs } from "node:fs";
import path from "node:path";
import { fileURLToPath } from "node:url";
import {
  ErrorCodes,
  PROTOCOL_VERSION,
  ProtocolSchemas,
} from "../src/gateway/protocol/schema.js";

type JsonSchema = {
  type?: string | string[];
  properties?: Record<string, JsonSchema>;
  required?: string[];
  items?: JsonSchema;
  enum?: string[];
  patternProperties?: Record<string, JsonSchema>;
};

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const repoRoot = path.resolve(__dirname, "..");
const outPath = path.join(
  repoRoot,
  "apps",
  "macos",
  "Sources",
  "ClawdisProtocol",
  "GatewayModels.swift",
);

const header = `// Generated by scripts/protocol-gen-swift.ts — do not edit by hand\nimport Foundation\n\npublic let GATEWAY_PROTOCOL_VERSION = ${PROTOCOL_VERSION}\n\npublic enum ErrorCode: String, Codable {\n${Object.values(ErrorCodes)
  .map((c) => `    case ${camelCase(c)} = "${c}"`)
  .join("\n")}\n}\n`;

function camelCase(input: string) {
  return input
    .toLowerCase()
    .split("_")
    .map((p, i) => (i === 0 ? p : p[0].toUpperCase() + p.slice(1)))
    .join("");
}

function swiftType(schema: JsonSchema, required: boolean): string {
  const t = schema.type;
  const isOptional = !required;
  let base: string;
  if (t === "string") base = "String";
  else if (t === "integer") base = "Int";
  else if (t === "number") base = "Double";
  else if (t === "boolean") base = "Bool";
  else if (t === "array") {
    base = `[${swiftType(schema.items ?? { type: "Any" }, true)}]`;
  } else if (schema.enum) {
    base = schema.enum.map((v) => `\"${v}\"`).join(" | ");
    base = "String"; // simplify enums to String; custom enums could be added if needed
  } else if (schema.patternProperties) {
    base = "[String: AnyCodable]";
  } else if (t === "object") {
    base = "[String: AnyCodable]";
  } else {
    base = "AnyCodable";
  }
  return isOptional ? `${base}?` : base;
}

function emitStruct(name: string, schema: JsonSchema): string {
  const props = schema.properties ?? {};
  const required = new Set(schema.required ?? []);
  const lines: string[] = [];
  lines.push(`public struct ${name}: Codable {`);
  if (Object.keys(props).length === 0) {
    lines.push("}\n");
    return lines.join("\n");
  }
  for (const [key, propSchema] of Object.entries(props)) {
    const propName = key === "description" ? "desc" : key;
    const propType = swiftType(propSchema, required.has(key));
    lines.push(`    public let ${propName}: ${propType}`);
  }
  lines.push("\n    public init(\n" +
    Object.entries(props)
      .map(([key, prop]) => {
        const propName = key === "description" ? "desc" : key;
        const req = required.has(key);
        return `        ${propName}: ${swiftType(prop, true)}${req ? "" : "?"}`;
      })
      .join(",\n") +
    "\n    ) {\n" +
    Object.entries(props)
      .map(([key]) => {
        const propName = key === "description" ? "desc" : key;
        return `        self.${propName} = ${propName}`;
      })
      .join("\n") +
    "\n    }\n}");
  lines.push("");
  return lines.join("\n");
}

function emitGatewayFrame(): string {
  const cases = [
    "hello",
    "hello-ok",
    "hello-error",
    "req",
    "res",
    "event",
  ];
  const associated: Record<string, string> = {
    hello: "Hello",
    "hello-ok": "HelloOk",
    "hello-error": "HelloError",
    req: "RequestFrame",
    res: "ResponseFrame",
    event: "EventFrame",
  };
  const caseLines = cases.map((c) => `    case ${camelCase(c)}(${associated[c]})`);
  const initLines = `
    public init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        let raw = try container.decode([String: AnyCodable].self)
        guard let type = raw["type"]?.value as? String else {
            throw DecodingError.dataCorruptedError(in: container, debugDescription: "missing type")
        }
        switch type {
        case "hello":
            self = .hello(try decodePayload(Hello.self, from: raw))
        case "hello-ok":
            self = .helloOk(try decodePayload(HelloOk.self, from: raw))
        case "hello-error":
            self = .helloError(try decodePayload(HelloError.self, from: raw))
        case "req":
            self = .req(try decodePayload(RequestFrame.self, from: raw))
        case "res":
            self = .res(try decodePayload(ResponseFrame.self, from: raw))
        case "event":
            self = .event(try decodePayload(EventFrame.self, from: raw))
        default:
            self = .unknown(type: type, raw: raw)
        }
    }

    public func encode(to encoder: Encoder) throws {
        switch self {
        case .hello(let v): try v.encode(to: encoder)
        case .helloOk(let v): try v.encode(to: encoder)
        case .helloError(let v): try v.encode(to: encoder)
        case .req(let v): try v.encode(to: encoder)
        case .res(let v): try v.encode(to: encoder)
        case .event(let v): try v.encode(to: encoder)
        case .unknown(_, let raw):
            var container = encoder.singleValueContainer()
            try container.encode(raw)
        }
    }
`;

  const helper = `
    private func decodePayload<T: Decodable>(_ type: T.Type, from raw: [String: AnyCodable]) throws -> T {
        let data = try JSONSerialization.data(withJSONObject: raw)
        let decoder = JSONDecoder()
        return try decoder.decode(T.self, from: data)
    }
`;

  return [
    "public enum GatewayFrame: Codable {",
    ...caseLines,
    "    case unknown(type: String, raw: [String: AnyCodable])",
    initLines,
    helper,
    "}",
    "",
  ].join("\n");
}

async function generate() {
  const definitions = Object.entries(ProtocolSchemas) as Array<
    [string, JsonSchema]
  >;

  const parts: string[] = [];
  parts.push(header);

  // Value structs
  for (const [name, schema] of definitions) {
    if (name === "GatewayFrame") continue;
    if (schema.type === "object") {
      parts.push(emitStruct(name, schema));
    }
  }

  // Frame enum must come after payload structs
  parts.push(emitGatewayFrame());

  const content = parts.join("\n");
  await fs.mkdir(path.dirname(outPath), { recursive: true });
  await fs.writeFile(outPath, content);
  console.log(`wrote ${outPath}`);
}

generate().catch((err) => {
  console.error(err);
  process.exit(1);
});