import type { BindingSchema } from "./index.js";
import type {
  ValueType,
  ObjectExpectation,
  PackageExport,
  DependencyPort,
  ExecutionContract,
} from "../capability-model/types.js";
import { hexDigest } from "../execution-world/plan.js";

export class PortableBindingError extends Error {
  constructor(
    readonly path: string,
    message: string,
  ) {
    super(`${path}: ${message}`);
    this.name = "PortableBindingError";
  }
}
const q = JSON.stringify;
const unit: ValueType = { kind: "builtin", name: "unit" };
const string: ValueType = { kind: "scalar", name: "string" };
const bool: ValueType = { kind: "scalar", name: "bool" };
const isUnit = (t: ValueType) => t.kind === "builtin" && t.name === "unit";
const expectation = (e: ObjectExpectation) => ({
  kind: e.kind,
  id: e.kind === "atom" ? e.atomId : e.interfaceRevisionId,
});
/** The protocol IR and replica wire schema intentionally share structure, not reference identity. */
export function portableValueSchema(type: ValueType): unknown {
  switch (type.kind) {
    case "change":
      return {
        kind: "record",
        fields: {
          codec: { kind: "scalar", name: "string" },
          profile: { kind: "scalar", name: "string" },
          generation: { kind: "scalar", name: "string" },
          changes: { kind: "list", value: { kind: "scalar", name: "bytes" } },
        },
      };
    case "scalar":
      return type;
    case "builtin":
      if (type.name === "unit") return type;
      break;
    case "object-ref":
      return { kind: type.kind, expectation: expectation(type.expectation) };
    case "optional":
    case "list":
      return { kind: type.kind, value: portableValueSchema(type.value) };
    case "record":
      return {
        kind: type.kind,
        fields: Object.fromEntries(
          Object.entries(type.fields).map(([key, value]) => [key, portableValueSchema(value)]),
        ),
      };
  }
  throw new PortableBindingError(
    type.kind,
    "Unsupported portable value; use a supported record/reference contract (native edits and generic adapters have separate tasks)",
  );
}
export function tsType(type: ValueType): string {
  portableValueSchema(type);
  switch (type.kind) {
    case "change":
      return `PreparedChange<${tsType(type.value)}>`;
    case "scalar":
      return type.name === "bool"
        ? "boolean"
        : type.name === "string"
          ? "string"
          : type.name === "bytes"
            ? "Uint8Array"
            : ["int64", "uint64"].includes(type.name)
              ? "bigint"
              : "number";
    case "builtin":
      return "null";
    case "object-ref": {
      const e = expectation(type.expectation);
      return `ManagedReference<${q(e.kind)}, ${q(e.id)}>`;
    }
    case "optional":
      return `(${tsType(type.value)} | null)`;
    case "list":
      return `ReadonlyArray<${tsType(type.value)}>`;
    case "record":
      return `{ ${Object.entries(type.fields)
        .map(([key, value]) => `readonly ${q(key)}: ${tsType(value)}`)
        .join("; ")} }`;
    default:
      throw new PortableBindingError(type.kind, "Unsupported type");
  }
}
interface Method {
  name: string;
  portId: string;
  portName: string;
  action: { kind: string; primitive?: string; operationId?: string };
  input: ValueType;
  output: ValueType;
  keyed: boolean;
}
function methods(schema: BindingSchema, entry: PackageExport, port: DependencyPort, target: string): Method[] {
  const req = port.requirement;
  const path = `${entry.displayName}.ports.${port.displayName}`;
  const method = (
    name: string,
    action: Method["action"],
    input: ValueType,
    output: ValueType,
    keyed = false,
  ): Method => ({ name, portId: port.id, portName: port.displayName, action, input, output, keyed });
  const writable = () => {
    if (entry.execution?.kind !== "transaction")
      throw new PortableBindingError(path, "Snapshot context cannot expose mutation ports");
  };
  switch (req.kind) {
    case "creation":
      writable();
      return [
        method(
          "create",
          { kind: "creation" },
          req.inputType,
          { kind: "object-ref", expectation: { kind: "atom", atomId: req.atomId } },
          true,
        ),
      ];
    case "state":
      return req.primitives.map((primitive) => {
        if (primitive === "read") return method("get", { kind: "state", primitive }, unit, req.valueType);
        if (primitive === "write") {
          writable();
          return method("set", { kind: "state", primitive }, req.valueType, unit);
        }
        if (primitive === "edit") {
          writable();
          return method("edit", { kind: "state", primitive }, { kind: "change", value: req.valueType }, unit);
        }
        throw new PortableBindingError(path, `State ${primitive} is not supported by this portable adapter yet`);
      });
    case "edge": {
      const ref: ValueType = { kind: "object-ref", expectation: req.target };
      const item: ValueType = { kind: "record", fields: { entry: string, target: ref } };
      return req.primitives.map((primitive) => {
        if (primitive === "resolve")
          return method("resolve", { kind: "edge", primitive }, unit, { kind: "list", value: item });
        writable();
        if (primitive === "connect") return method("connect", { kind: "edge", primitive }, ref, string, true);
        if (primitive === "disconnect") return method("disconnect", { kind: "edge", primitive }, string, bool);
        throw new PortableBindingError(path, `Edge ${primitive} is not supported by this portable adapter yet`);
      });
    }
    case "interface": {
      const iface = schema.interfaces.find((i) => i.revisionId === req.interfaceRevisionId);
      if (!iface) throw new PortableBindingError(path, `Missing interface ${req.interfaceRevisionId}`);
      const operations = iface.members.flatMap((member) => member.operations.map((op) => ({ member, op })));
      if (req.operations?.some((id) => !operations.some(({ op }) => op.id === id)))
        throw new PortableBindingError(path, "Unknown selected interface operation");
      return operations
        .filter(({ op }) => !req.operations || req.operations.includes(op.id))
        .map(({ member, op }) => {
          const execution: ExecutionContract = op.execution ?? { kind: "remote" };
          if (
            execution.kind === "remote" ||
            !execution.targets.includes(target) ||
            op.mode !== "call" ||
            op.scope === "class"
          )
            throw new PortableBindingError(
              `${path}.${member.displayName}.${op.displayName}`,
              `Selected operation is not an object call available in portable target ${target}; select a portable subset or move this handler to remote execution`,
            );
          if (execution.kind === "transaction") writable();
          return method(
            `${member.displayName}.${op.displayName}`,
            { kind: "interface", operationId: op.id },
            op.inputType,
            op.outputType,
            execution.kind === "transaction",
          );
        });
    }
    default:
      throw new PortableBindingError(path, `Unsupported ${req.kind} port in portable bindings`);
  }
}
export interface PortableBindingOptions {
  target: string;
  runtimeModule?: string;
}
/** Generate one target's handlers. The same source signatures are used in browser/server builds. */
export function generatePortableTypeScriptBindings(
  schema: BindingSchema,
  revision: string,
  options: PortableBindingOptions,
): string {
  const pkg = schema.packages.find((p) => p.revisionId === revision);
  if (!pkg) throw new PortableBindingError(revision, "Missing package");
  const entries = pkg.exports.filter(
    (e) => e.execution && e.execution.kind !== "remote" && e.execution.targets.includes(options.target),
  );
  const names = new Set<string>();
  const contexts: string[] = [],
    implementations: string[] = [],
    adapters: string[] = [],
    descriptors: unknown[] = [];
  for (const entry of entries) {
    // The checked binding schema already contains concrete generic applications.
    // Each has its own identity, value codecs and specialized dependency ports.
    if (entry.kind === "constructor")
      throw new PortableBindingError(entry.id, "Legacy constructors are not supported; declare an ordinary factory");
    if (names.has(entry.displayName)) throw new PortableBindingError(entry.id, "Duplicate handler name");
    names.add(entry.displayName);
    const portNames = new Set<string>();
    const all: Method[] = [],
      facets: string[] = [];
    for (const port of entry.dependencyPorts) {
      if (portNames.has(port.displayName))
        throw new PortableBindingError(entry.id, `Duplicate port name ${port.displayName}`);
      portNames.add(port.displayName);
      const selected = methods(schema, entry, port, options.target);
      if (new Set(selected.map((m) => m.name)).size !== selected.length)
        throw new PortableBindingError(port.id, "Duplicate method name");
      all.push(...selected);
      facets.push(
        `readonly ${q(port.displayName)}: { ${selected.map((m) => `readonly ${q(m.name)}: (${[...(isUnit(m.input) ? [] : [`input: ${tsType(m.input)}`]), ...(m.keyed ? ["options: MutationKey"] : [])].join(", ")}) => Promise<${tsType(m.output)}>`).join("; ")} }`,
      );
    }
    const receiver =
      entry.kind === "function"
        ? null
        : entry.receiverRequirement.kind === "exact-atom"
          ? { kind: "atom", id: entry.receiverRequirement.atomId }
          : "object";
    const receiverType =
      receiver === null
        ? "null"
        : receiver === "object"
          ? "ExactReference"
          : `ManagedReference<"atom", ${q(receiver.id)}>`;
    contexts.push(
      `readonly ${q(entry.displayName)}: { readonly effect: ${q(entry.execution!.kind)}; readonly input: ${tsType(entry.inputType)}; readonly receiver: ${receiverType}; readonly ports: { ${facets.join("; ")} } }`,
    );
    const output = tsType(entry.outputType);
    implementations.push(
      `readonly ${q(entry.displayName)}: (context: Contexts[${q(entry.displayName)}]) => ${output} | Promise<${output}>`,
    );
    adapters.push(
      `${q(entry.id)}: context => installed[${q(entry.displayName)}](context as Contexts[${q(entry.displayName)}])`,
    );
    descriptors.push({
      id: entry.id,
      name: entry.displayName,
      effect: entry.execution!.kind,
      receiver,
      input: portableValueSchema(entry.inputType),
      output: portableValueSchema(entry.outputType),
      methods: all.map((m) => ({ ...m, input: portableValueSchema(m.input), output: portableValueSchema(m.output) })),
    });
  }
  return `// Generated portable bindings. Regenerate from the checked capability schema; do not edit.\nimport { definePortableRegistry, type PortableExport, type PreparedChange, type ManagedReference, type ExactReference, type MutationKey } from ${q(options.runtimeModule ?? "@quixos/camino-replica-core")};\nexport const bindingDigest = ${q(hexDigest(schema))};\nexport const packageRevision = ${q(revision)};\nexport const target = ${q(options.target)};\nexport type Contexts = { ${contexts.join(";\n")} };\nexport type PortableImplementation = { ${implementations.join(";\n")} };\nexport const declarations = ${JSON.stringify(descriptors, null, 2)} as const satisfies readonly PortableExport[];\nexport function createRegistry(handlers: PortableImplementation) { const installed = { ...handlers }; return definePortableRegistry(declarations, { ${adapters.join(",\n")} }); }\n`;
}