import type { BindingSchema } from "./index.js";
import type { ValueType } from "../capability-model/types.js";

/** Browser projection of the SAME checked RPC types, not a second props schema. */
export function generateReactBindings(
  schema: BindingSchema,
  packageRevisionId: string,
  propsExports: readonly string[],
  components: readonly { module: string; propsExport: string }[] = [],
) {
  const pkg = schema.packages.find((entry) => entry.revisionId === packageRevisionId);
  if (!pkg) throw new Error(`Unknown package ${packageRevisionId}`);
  const q = JSON.stringify;
  const references = new Map<string, string>();
  const declarations: string[] = [];
  const type = (value: ValueType): string => {
    switch (value.kind) {
      case "variant":
        throw new Error("Variants require the Camino portable value runtime; legacy RPC bindings are unsupported");
      case "builtin":
        if (value.name !== "unit") throw new Error(`Unsupported React props builtin ${value.name}`);
        return "null";
      case "scalar":
        return {
          string: "string",
          bool: "boolean",
          bytes: "Uint8Array",
          int64: "bigint",
          uint64: "bigint",
          int32: "number",
          uint32: "number",
          double: "number",
        }[value.name];
      case "change":
        throw new Error("CRDT change values require the prepared-change codec and runtime (LF-19)");
      case "optional":
        return `(${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":
        throw new Error(`React props require checked values, not opaque message ${value.descriptorId}`);
      case "object-ref": {
        if (value.expectation.kind === "atom") return `ObjectRef<${q(value.expectation.atomId)}>`;
        const id = value.expectation.interfaceRevisionId;
        const existing = references.get(id);
        if (existing) return existing;
        const name = `Interface${references.size}`;
        references.set(id, name);
        const iface = schema.interfaces.find((entry) => entry.revisionId === id);
        if (!iface) throw new Error(`Missing React reference contract ${id}`);
        const fields = iface.members.flatMap((member) => {
          if (member.kind === "operation") return [];
          const get = member.operations.find((op) => op.displayName === (member.kind === "value" ? "get" : "resolve"));
          if (!get) return [];
          const writable = member.kind === "value" && member.operations.some((op) => op.displayName === "set");
          return [`${q(member.displayName)}: ${writable ? "WritableField" : "ReadableField"}<${type(get.outputType)}>`];
        });
        declarations.push(`export type ${name} = InterfaceReference<${q(id)}, {${fields.join(";")}}> ;`);
        return name;
      }
    }
  };
  // Only exports explicitly selected as props are projected. Non-props exports
  // may legitimately use opaque messages or types unrelated to the browser.
  const selected = propsExports.map((name) => {
    const entry = pkg.exports.find((candidate) => candidate.displayName === name);
    if (!entry) throw new Error(`Unknown React props export ${name}`);
    return entry;
  });
  const results = selected.map(
    (entry) =>
      `${q(entry.displayName)}: ${type(entry.kind === "operation" ? (entry.eventType ?? entry.outputType) : entry.outputType)}`,
  );
  const checks = components.map((component, i) => {
    if (!propsExports.includes(component.propsExport))
      throw new Error(`Component refers to unselected props export ${component.propsExport}`);
    if (!component.module.startsWith("."))
      throw new Error("React component check must name a local module relative to generated bindings");
    return `type Component${i} = CheckedComponent<${q(component.propsExport)}, typeof import(${q(component.module)})["default"]>;`;
  });
  // Emit optional discovery descriptors only when the browser has all codecs.
  // Unrelated opaque-message imports must not break an otherwise checked UI.
  const browserValue = (value: ValueType, seen: Set<string>): boolean => {
    if (value.kind === "message") return false;
    if (value.kind === "builtin") return value.name === "unit";
    if (value.kind === "variant") return false;
    if (value.kind === "record") return Object.values(value.fields).every((field) => browserValue(field, seen));
    if (value.kind === "list" || value.kind === "optional") return browserValue(value.value, seen);
    if (value.kind === "object-ref" && value.expectation.kind === "interface") {
      const id = value.expectation.interfaceRevisionId;
      if (seen.has(id)) return true;
      const contract = schema.interfaces.find((entry) => entry.revisionId === id);
      return !!contract && browserInterface(contract, new Set([...seen, id]));
    }
    return true;
  };
  const browserInterface = (iface: (typeof schema.interfaces)[number], seen: Set<string>): boolean =>
    iface.members.every((member) =>
      member.operations
        .filter((op) => op.mode === "call" && op.scope !== "class")
        .every((op) => browserValue(op.inputType, seen) && browserValue(op.outputType, seen)),
    );
  const contracts = schema.interfaces
    .filter((iface) => browserInterface(iface, new Set([iface.revisionId])))
    .map((iface) => {
      const reference = type({
        kind: "object-ref",
        expectation: { kind: "interface", interfaceRevisionId: iface.revisionId },
      });
      const calls = iface.members.flatMap((member) =>
        member.operations
          .filter((operation) => operation.mode === "call" && operation.scope !== "class")
          .map(
            (operation) =>
              `${q(`${member.displayName}.${operation.displayName}`)}: (${operation.inputType.kind === "builtin" && operation.inputType.name === "unit" ? "" : `input: ${type(operation.inputType)}`}) => Promise<${type(operation.outputType)}>`,
          ),
      );
      return { iface, view: `${reference} & {call: {${calls.join(";")}}}` };
    });
  const queryType = (value: ValueType): string => {
    if (value.kind === "object-ref")
      return `QueryReference<${q(value.expectation.kind === "atom" ? value.expectation.atomId : value.expectation.interfaceRevisionId)}>`;
    if (value.kind === "optional") return `(${queryType(value.value)} | null)`;
    if (value.kind === "list") return `Array<${queryType(value.value)}>`;
    if (value.kind === "record")
      return `{${Object.entries(value.fields)
        .map(([name, field]) => `${q(name)}: ${queryType(field)}`)
        .join(";")}}`;
    return type(value);
  };
  const queries = pkg.checkedQueries ?? [];
  const queryCode =
    `export type QueryVariables = {${queries.map((query) => `${q(query.declaration.displayName)}: ${queryType(query.variables)}`).join(";")}};\n` +
    `export type QueryResults = {${queries.map((query) => `${q(query.declaration.displayName)}: ${queryType(query.output)}`).join(";")}};\n` +
    `export const queries: {${queries.map((query) => `${q(query.declaration.displayName)}: QueryDescriptor<QueryVariables[${q(query.declaration.displayName)}], QueryResults[${q(query.declaration.displayName)}], ${q(query.declaration.root.kind)}>`).join(";")}} = ${JSON.stringify(
      Object.fromEntries(
        queries.map((query) => [
          query.declaration.displayName,
          {
            id: `${pkg.revisionId}:${query.declaration.id}`,
            definitionDigest: query.definitionDigest,
            root: query.declaration.root,
            variables: query.variables,
            output: query.output,
            watch: query.declaration.watch,
          },
        ]),
      ),
    )};\n`;
  return (
    `// Generated from checked QX contracts. Do not edit.\nimport {defineReactInterfaceContract} from "@quixos/web-studio-react-runtime";\nimport type {ObjectRef, InterfaceReference, ReadableField, WritableField, QueryField, WritableQueryField, QueryDescriptor, QueryReference} from "@quixos/web-studio-react-runtime";\n${declarations.join("\n")}\nexport type ReactResults = {${results.join(";\n")}};\n` +
    queryCode +
    `const contractsData = ${JSON.stringify(schema.interfaces)};\n` +
    `export const reactContracts = {${contracts.map(({ iface, view }) => `${q(iface.revisionId)}: defineReactInterfaceContract<${view}>(${q(iface.revisionId)}, contractsData)`).join(",\n")}};\n` +
    `export const reactInterfaces = {${contracts
      .filter(({ iface }) => contracts.filter((other) => other.iface.displayName === iface.displayName).length === 1)
      .map(({ iface }) => `${q(iface.displayName)}: reactContracts[${q(iface.revisionId)}]`)
      .join(",\n")}};\n` +
    (checks.length
      ? `type CheckedComponent<K extends keyof ReactResults, C extends (props: {camino: ReactResults[K]; render: any; dispatch: (action: any) => void}) => unknown> = C;\n${checks.join("\n")}\n`
      : "")
  );
}