import type { InterfaceRevision, ValueType } from "../capability-model/types.js";

/** Host clients have no package receiver, but must use the same checked
 * interface signatures and argument framing as generated package ports. */
export const generateClientContracts = (
  interfaces: InterfaceRevision[],
  messages: Record<string, string>,
  qualified = false,
) => {
  if (interfaces.some((entry) => entry.template))
    throw new Error("Host contracts require closed interface applications, not generic definitions");
  const type = (value: ValueType): string => {
    switch (value.kind) {
      case "builtin":
        return value.name === "unit" ? "undefined" : "string";
      case "scalar":
        return {
          bool: "boolean",
          string: "string",
          bytes: "Uint8Array",
          int32: "number",
          uint32: "number",
          double: "number",
          int64: "bigint",
          uint64: "bigint",
        }[value.name];
      case "object-ref":
        return qualified
          ? `CapabilityReference<${JSON.stringify(value.expectation.kind === "atom" ? `atom:${value.expectation.atomId}` : `interface:${value.expectation.interfaceRevisionId}`)}>`
          : `{readonly $quixosRef: string}`;
      case "optional":
        return `(${type(value.value)} | null)`;
      case "list":
        return `Array<${type(value.value)}>`;
      case "record":
        return `{${Object.entries(value.fields)
          .map(([name, field]) => `${JSON.stringify(name)}${field.kind === "optional" ? "?" : ""}: ${type(field)}`)
          .join("; ")}}`;
      case "message": {
        const binding = messages[value.descriptorId];
        if (!binding) throw new Error(`Missing host message type ${value.descriptorId}`);
        return binding;
      }
    }
  };
  const operations = interfaces.flatMap((iface) =>
    iface.members.flatMap((member) =>
      member.operations
        .filter((operation) => operation.mode === "call")
        .map((operation) => ({ ...operation, interfaceRevisionId: iface.revisionId })),
    ),
  );
  if (qualified) {
    const contracts = interfaces.map((iface) => {
      const members = iface.members.flatMap((member) =>
        member.operations
          .filter((op) => op.mode === "call")
          .map((op) => `  ${JSON.stringify(op.id)}: {input: ${type(op.inputType)}; output: ${type(op.outputType)}};`),
      );
      return `${JSON.stringify(iface.revisionId)}: {\n${members.join("\n")}\n}`;
    });
    if (new Set(interfaces.map((iface) => iface.revisionId)).size !== interfaces.length)
      throw new Error("Duplicate closed interface identity");
    return (
      `// Generated closed capability contracts. Dispatch by interface AND operation.\n` +
      `declare const referenceType: unique symbol;\nexport type CapabilityReference<T extends string> = {readonly $quixosRef: string; readonly [referenceType]: T};\n` +
      `export type CapabilityContracts = {${contracts.join(";\n")}};\n` +
      `export type CapabilityInput<I extends keyof CapabilityContracts, O extends keyof CapabilityContracts[I]> = CapabilityContracts[I][O] extends {input: infer T} ? T : never;\n` +
      `export type CapabilityOutput<I extends keyof CapabilityContracts, O extends keyof CapabilityContracts[I]> = CapabilityContracts[I][O] extends {output: infer T} ? T : never;\n` +
      `export const capabilityApplications = ${JSON.stringify(Object.fromEntries(interfaces.map((iface) => [iface.revisionId, { definitionId: iface.application?.definitionId ?? iface.revisionId, arguments: iface.application?.arguments ?? [], ...(iface.application?.self ? { self: iface.application.self } : {}) }])))} as const;\n`
    );
  }
  if (new Set(operations.map((entry) => entry.id)).size !== operations.length)
    throw new Error(
      "Host operation IDs are ambiguous across interfaces; select a closed interface application explicitly",
    );
  return (
    `// Generated from checked QX interfaces. Regenerate with scripts/generate-platform-contracts.mjs.\n` +
    `export type PlatformInputs = {\n${operations.map((operation) => `  ${JSON.stringify(operation.id)}: ${type(operation.inputType)};`).join("\n")}\n};\n` +
    `export const platformOperations = ${JSON.stringify(
      Object.fromEntries(
        operations.map((operation) => [
          operation.id,
          {
            interfaceRevisionId: operation.interfaceRevisionId,
            input:
              operation.inputType.kind === "builtin" && operation.inputType.name === "unit"
                ? "unit"
                : ["record", "message"].includes(operation.inputType.kind)
                  ? "fields"
                  : "value",
          },
        ]),
      ),
      null,
      2,
    )} as const;\n`
  );
};

/** New consumers use exact closed interface identities; operation IDs alone are not unique. */
export const generateAppliedClientContracts = (
  interfaces: InterfaceRevision[],
  messages: Record<string, string> = {},
) => generateClientContracts(interfaces, messages, true);