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`;

const reserved = new Set([
  "associatedtype",
  "class",
  "deinit",
  "enum",
  "extension",
  "fileprivate",
  "func",
  "import",
  "init",
  "inout",
  "internal",
  "let",
  "open",
  "operator",
  "private",
  "precedencegroup",
  "protocol",
  "public",
  "rethrows",
  "static",
  "struct",
  "subscript",
  "typealias",
  "var",
]);

function camelCase(input: string) {
  return input
    .replace(/[^a-zA-Z0-9]+/g, " ")
    .trim()
    .toLowerCase()
    .split(/\s+/)
    .map((p, i) => (i === 0 ? p : p[0].toUpperCase() + p.slice(1)))
    .join("");
}

function safeName(name: string) {
  const cc = camelCase(name.replace(/-/g, "_"));
  if (reserved.has(cc)) return `_${cc}`;
  return cc;
}

// filled later once schemas are loaded
const schemaNameByObject = new Map<object, string>();

function swiftType(schema: JsonSchema, required: boolean): string {
  const t = schema.type;
  const isOptional = !required;
  let base: string;
  const named = schemaNameByObject.get(schema as object);
  if (named) {
    base = named;
  } else 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 = `[${swiftType(schema.items ?? { type: "Any" }, true)}]`;
  } else if (schema.enum) {
    base = "String";
  } else if (schema.patternProperties) {
    base = "[String: AnyCodable]";
  } else if (t === "object") {
    base = "[String: AnyCodable]";
  } else {
    base = "AnyCodable";
  }
  return isOptional ? `${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");
  }
  const codingKeys: string[] = [];
  for (const [key, propSchema] of Object.entries(props)) {
    const propName = safeName(key);
    const propType = swiftType(propSchema, required.has(key));
    lines.push(`    public let ${propName}: ${propType}`);
    if (propName !== key) {
      codingKeys.push(`        case ${propName} = "${key}"`);
    } else {
      codingKeys.push(`        case ${propName}`);
    }
  }
  lines.push("\n    public init(\n" +
    Object.entries(props)
      .map(([key, prop]) => {
        const propName = safeName(key);
        const req = required.has(key);
        return `        ${propName}: ${swiftType(prop, true)}${req ? "" : "?"}`;
      })
      .join(",\n") +
    "\n    ) {\n" +
    Object.entries(props)
      .map(([key]) => {
        const propName = safeName(key);
        return `        self.${propName} = ${propName}`;
      })
      .join("\n") +
    "\n    }\n" +
    "    private enum CodingKeys: String, CodingKey {\n" +
    codingKeys.join("\n") +
    "\n    }\n}");
  lines.push("");
  return lines.join("\n");
}

function emitGatewayFrame(): string {
  const cases = ["req", "res", "event"];
  const associated: Record<string, string> = {
    req: "RequestFrame",
    res: "ResponseFrame",
    event: "EventFrame",
  };
  const caseLines = cases.map((c) => `    case ${safeName(c)}(${associated[c]})`);
  const initLines = `
    private enum CodingKeys: String, CodingKey {
        case type
    }

    public init(from decoder: Decoder) throws {
        let typeContainer = try decoder.container(keyedBy: CodingKeys.self)
        let type = try typeContainer.decode(String.self, forKey: .type)
        switch type {
        case "req":
            self = .req(try RequestFrame(from: decoder))
        case "res":
            self = .res(try ResponseFrame(from: decoder))
        case "event":
            self = .event(try EventFrame(from: decoder))
        default:
            let container = try decoder.singleValueContainer()
            let raw = try container.decode([String: AnyCodable].self)
            self = .unknown(type: type, raw: raw)
        }
    }

    public func encode(to encoder: Encoder) throws {
        switch self {
        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)
        }
    }
`;

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

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

  for (const [name, schema] of definitions) {
    schemaNameByObject.set(schema as object, name);
  }

  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);
});