import type { InterfaceRevision, PackageRevision, ValueType, DependencyPort } from "../capability-model/types.js";
import type { CompiledCapabilityResourceRepository } from "../capability-language/assembly.js";

/** Portable generator input. New backends consume this instead of the parser or TS runtime. */
export type BindingSchema = {
  format: "quixos-bindings";
  version: 1;
  interfaces: InterfaceRevision[];
  packages: PackageRevision[];
};
export const bindingSchema = (compiled: CompiledCapabilityResourceRepository): BindingSchema => ({
  format: "quixos-bindings", version: 1,
  interfaces: compiled.resources.flatMap((node) => node.resource.kind === "interface" ? [node.resource.revision] : []),
  packages: compiled.resources.flatMap((node) => node.resource.kind === "package" ? [node.resource.revision] : []),
});
export type TypeScriptBindingOptions = {
  runtimeModule?: string;
  /** Each export must implement MessageBinding<T>, providing both TS type and wire codec. */
  messages?: Record<string, { module: string; export: string }>;
};
export function generatePackageDescriptor(schema: BindingSchema, revisionId: string): string {
  const pkg = schema.packages.find(entry => entry.revisionId === revisionId);
  if (!pkg) throw new Error(`Unknown package revision ${revisionId}`);
  return `# Generated from the checked package contract\npackage_id: ${JSON.stringify(pkg.packageId)}\npackage_revision_id: ${JSON.stringify(pkg.revisionId)}\nruntime_protocol_version: "quixos-capabilities-v1"\n` +
    pkg.exports.map(entry => `exports: { export_id: ${JSON.stringify(entry.id)} runtime_symbol: ${JSON.stringify(entry.displayName)} }\n`).join("");
}
const q = JSON.stringify;
const object = (entries: [string, string][]) => `{ ${entries.map(([key, value]) => `${q(key)}: ${value}`).join("; ")} }`;
const unit = (type: ValueType) => type.kind === "builtin" && type.name === "unit";

export const generateTypeScriptBindings = (
  schema: BindingSchema, packageRevisionId: string, options: TypeScriptBindingOptions = {},
) => {
  if (schema.format !== "quixos-bindings" || schema.version !== 1) throw new Error("Unsupported binding schema version");
  const pkg = schema.packages.find((entry) => entry.revisionId === packageRevisionId);
  if (!pkg) throw new Error(`Unknown package revision ${packageRevisionId}`);
  const messages = new Map<string, string>();
  const type = (value: ValueType): string => {
    switch (value.kind) {
      case "builtin": return value.name === "unit" ? "null" : "QxWatchHandle";
      case "scalar": return ({ bool: "boolean", bytes: "Uint8Array", string: "string", int64: "bigint", uint64: "bigint",
        double: "number", int32: "number", uint32: "number" })[value.name];
      case "object-ref": return `QxObjectRef<${q(value.expectation.kind === "atom" ? `atom:${value.expectation.atomId}` : `interface:${value.expectation.interfaceRevisionId}`)}>`;
      case "optional": return `(${type(value.value)} | null)`;
      case "list": return `Array<${type(value.value)}>`;
      case "record": return `{ ${Object.entries(value.fields).map(([name, field]) => `${q(name)}: ${type(field)}`).join("; ")} }`;
      case "message": {
        if (!options.messages?.[value.descriptorId]) throw new Error(`Missing TypeScript message binding for ${value.descriptorId}`);
        if (!messages.has(value.descriptorId)) messages.set(value.descriptorId, `message${messages.size}`);
        return `BindingValue<typeof ${messages.get(value.descriptorId)}>`;
      }
    }
  };
  const ref = (target: { kind: "atom"; atomId: string } | { kind: "interface"; interfaceRevisionId: string }) =>
    `QxObjectRef<${q(target.kind === "atom" ? `atom:${target.atomId}` : `interface:${target.interfaceRevisionId}`)}>`;
  const params = (input: ValueType) => unit(input) ? "" : `input: ${type(input)}`;
  const port = (entry: DependencyPort): { type: string; spec: unknown } => {
    const requirement = entry.requirement;
    switch (requirement.kind) {
      case "state": {
        const methods = requirement.primitives.map((primitive): [string, string] => {
          if (primitive === "read") return ["get", `() => Promise<${type(requirement.valueType)}>`];
          if (primitive === "write") return ["set", `(value: ${type(requirement.valueType)}) => Promise<void>`];
          throw new Error(`State primitive ${primitive} is not supported by the TypeScript runtime binding yet`);
        });
        if (requirement.primitives.includes("read")) methods.push(["live", "() => Promise<QxLiveValue>"]);
        return { type: object(methods), spec: { ...requirement, id: entry.id } };
      }
      case "edge": {
        const methods = requirement.primitives.map((primitive): [string, string] => {
          if (primitive === "resolve") return [primitive, `() => Promise<Array<${ref(requirement.target)}>>`];
          if (primitive === "connect" || primitive === "disconnect") return [primitive, `(target: ${ref(requirement.target)}) => Promise<void>`];
          throw new Error(`Edge primitive ${primitive} is not supported by the TypeScript runtime binding yet`);
        });
        if (requirement.primitives.includes("resolve")) methods.push(["collection", `() => Promise<RelationshipCollection<${ref(requirement.target)}>>`]);
        if (["resolve", "connect", "disconnect"].every((primitive) => requirement.primitives.includes(primitive as "resolve"))) methods.push(["replace", `(entries: RelationshipEntry<${ref(requirement.target)}>[], expectedRevision: bigint) => Promise<RelationshipCollection<${ref(requirement.target)}>>`]);
        return { type: object(methods), spec: { kind: "edge", id: entry.id, primitives: requirement.primitives } };
      }
      case "interface": {
        const contract = schema.interfaces.find((candidate) => candidate.revisionId === requirement.interfaceRevisionId);
        if (!contract) throw new Error(`Missing imported interface contract ${requirement.interfaceRevisionId}`);
        // Streaming ports need a future streaming ABI; ordinary calls are fully typed today.
        const operations = contract.members.flatMap((member) => member.operations.filter((operation) => operation.mode === "call")
          .map((operation) => ({ ...operation, name: `${member.displayName}.${operation.displayName}` })));
        return { type: object([
          ["objectId", ref({ kind: "interface", interfaceRevisionId: requirement.interfaceRevisionId })],
          ["live", object(operations.map(operation => [operation.name, `(${params(operation.inputType)}) => Promise<QxLiveValue>`]))],
          ...operations.map((operation): [string, string] => [operation.name, `(${params(operation.inputType)}) => Promise<${type(operation.outputType)}>`]),
        ]),
          spec: { kind: "interface", id: entry.id, operations: Object.fromEntries(operations.map(({name, id, inputType, outputType}) =>
            [name, {id, inputType, outputType}])) } };
      }
      case "constructor": {
        const input = requirement.inputType;
        if (!input) throw new Error(`Constructor port ${entry.id} needs an explicit input contract: add 'input TYPE' after ${requirement.atomId} in QX`);
        return { type: object([["construct", `(${params(input)}) => Promise<${ref({ kind: "atom", atomId: requirement.atomId })}>`]]),
          spec: { kind: "constructor", id: entry.id, inputType: input } };
      }
    }
  };
  const exports = [...pkg.exports].sort((a, b) => a.id < b.id ? -1 : a.id > b.id ? 1 : 0);
  const names = new Set<string>();
  const specs: Record<string, unknown> = {};
  const contexts: [string, string][] = [];
  const handlers: [string, string][] = [];
  for (const entry of exports) {
    if (names.has(entry.displayName)) throw new Error(`Duplicate export name ${entry.displayName}`);
    names.add(entry.displayName);
    const ports = entry.dependencyPorts.map((dependency) => ({ name: dependency.displayName, ...port(dependency) }));
    if (new Set(ports.map((p) => p.name)).size !== ports.length) throw new Error(`Duplicate dependency name in ${entry.displayName}`);
    const receiver = entry.kind === "constructor" ? ref({ kind: "atom", atomId: entry.constructsAtom }) :
      entry.kind === "operation" && entry.receiverRequirement.kind === "exact-atom" ?
        ref({ kind: "atom", atomId: entry.receiverRequirement.atomId }) :
      entry.kind === "operation" && entry.receiverRequirement.kind === "all-interfaces" ?
        `QxObjectRef<${entry.receiverRequirement.interfaceRevisionIds.map((id) => q(`interface:${id}`)).join(" | ") || "never"}>` : "QxObjectRef<string>";
    const contextShape = object([["objectId", receiver], ["input", type(entry.inputType)],
      ["ports", object(ports.map((port) => [port.name, port.type]))]]);
    contexts.push([entry.displayName, `${contextShape} & QxContextLifecycle<${contextShape} & {signal?: AbortSignal}>`]);
    const event = entry.kind === "operation" ? entry.eventType : undefined;
    const contextType = `Contexts[${q(entry.displayName)}]`;
    const outputType = type(event ?? entry.outputType);
    // Watch-start handlers produce events through the runtime's derived stream protocol.
    handlers.push([entry.displayName, event ? `QxDerived<${contextType}, ${outputType}>` :
      `QxHandler<${contextType}, ${outputType}>${entry.kind === "operation" && entry.mode === "call" ? ` | QxDerived<${contextType}, ${outputType}>` : ""}`]);
    specs[entry.displayName] = { inputType: entry.inputType, outputType: entry.outputType,
      ...(event ? { eventType: event } : {}), ports: Object.fromEntries(ports.map((port) => [port.name, port.spec])) };
  }
  const imports = [...messages].map(([id, alias]) => {
    const binding = options.messages![id]!;
    if (!/^[A-Za-z_$][A-Za-z0-9_$]*$/.test(binding.export)) throw new Error(`Invalid message binding export ${binding.export}`);
    return `import { ${binding.export} as ${alias} } from ${q(binding.module)};`;
  });
  const signatures = `${object(contexts)} ${object(handlers)}`;
  const typeImports = ["BindingValue", "QxObjectRef", "QxWatchHandle", "QxHandler", "QxDerived", "QxContextLifecycle", "QxLiveValue", "RelationshipCollection", "RelationshipEntry"].filter((name) => new RegExp(`\\b${name}\\b`).test(signatures));
  return `// Generated by quixos-codegen-ts. Do not edit. Binding ABI version 1.\n` +
    `import { ${exports.length ? "bindQxHandler, " : ""}${[...typeImports, "QxHandlerSpec", "QxMessages"].map((name) => `type ${name}`).join(", ")} } from ${q(options.runtimeModule ?? "@quixos/camino-package-runtime")};\n` +
    imports.join("\n") + `\nexport const packageRevisionId = ${q(pkg.revisionId)};\n` +
    `export type Contexts = ${object(contexts)};\nexport type Implementation = ${object(handlers)};\n` +
    `const messages = { ${[...messages].map(([id, alias]) => `${q(id)}: ${alias}`).join(", ")} } satisfies QxMessages;\n` +
    `const specs = ${JSON.stringify(specs, null, 2)} satisfies Record<string, QxHandlerSpec>;\n` +
    `export const createRuntime = (implementation: Implementation) => ({\n  packageRevisionId,\n  exports: {\n` +
    exports.map((entry) => `    ${q(entry.id)}: bindQxHandler(specs[${q(entry.displayName)}], implementation[${q(entry.displayName)}], messages),`).join("\n") +
    `\n  },\n});\n`;
};