import type { InterfaceRevision, PackageRevision, ValueType } from "../capability-model/types.js";
import type { QueryBinding, QueryComposition, QueryCompositionStep } from "../query/composition.js";

/** This is an artifact of the explicitly selected React frontend, not QX IR. */
export const preparationArtifact = "org.quixos.react.preparation/1";
export interface ReactChildDeclaration {
  name: string;
  subject: string;
  root: QueryBinding;
  slot: string;
  with?: QueryBinding;
  each?: { source: QueryBinding; limit: number };
  when?: QueryBinding;
  role?: { interface: string; member: string };
  provider?: { package: string; module: string };
}
export interface ReactModulePreparation {
  module: string;
  composition: string;
  /** Public input type before workspace query lowering adds private projections. */
  input?: ValueType;
  children: ReactChildDeclaration[];
  /** Binds roots/arguments only. The ordinary checked Query Tree owns every
   * acquisition path; the React declaration does not repeat its descendants. */
  trees?: Pick<QueryCompositionStep, "name" | "query" | "root" | "arguments">[];
}
export interface ReactPreparationArtifact {
  /** Frontend queries belong to installed preparation, not the authored client API. */
  internalQueries?: string[];
  modules: ReactModulePreparation[];
}

/** Names are package imports/module declarations. All query bindings are passed
 * to Camino's ordinary composition checker after generated queries are checked. */
export function presentationDeclarations(
  text: string,
  pkg: PackageRevision,
  interfaces: readonly InterfaceRevision[],
): { compositions: QueryComposition[]; artifact: ReactPreparationArtifact } {
  const source: unknown = JSON.parse(text);
  const object = (value: unknown, label: string): Record<string, unknown> => {
    if (!value || typeof value !== "object" || Array.isArray(value)) throw Error(`${label}: expected an object`);
    return value as Record<string, unknown>;
  };
  const top = object(source, "quixos.react.json");
  if (Object.keys(top).some((key) => key !== "modules")) throw Error("quixos.react.json: unknown field");
  const modules = object(top.modules, "modules");
  const compositions: QueryComposition[] = [];
  const artifact: ReactPreparationArtifact = { modules: [] };
  const imported = (name: string) => {
    const id = pkg.clientInterfaces?.[name];
    if (!id) throw Error(`React declaration: unknown imported interface ${name}`);
    return id;
  };
  for (const [name, value] of Object.entries(modules)) {
    const declaration = object(value, `module ${name}`);
    if (Object.keys(declaration).some((key) => !["inputs", "children", "trees"].includes(key)))
      throw Error(`${name}: unknown preparation field`);
    const module = pkg.modules?.find((entry) => entry.displayName === name);
    if (!module) throw Error(`React declaration: unknown module ${name}`);
    const contract = interfaces.find((entry) => entry.revisionId === module.interfaceRevisionId);
    const member = contract?.members.find((entry) => entry.id === module.memberId);
    if (
      member?.kind !== "module" ||
      member.subject?.kind !== "interface" ||
      !["org.quixos.react.component/1", "org.quixos.react.component/2", "org.quixos.react.subject-only/1"].includes(
        member.contract,
      )
    )
      throw Error(`${name}: preparation requires a React module contract`);
    const fields: Record<string, ValueType> = {
      subject: {
        kind: "object-ref",
        expectation: { kind: "interface", interfaceRevisionId: member.subject.interfaceRevisionId },
      },
    };
    if (member.contract === "org.quixos.react.component/2") {
      const state = contract?.application?.arguments[1];
      if (state?.kind !== "object" || state.target.kind !== "interface")
        throw Error(`${name}: expected a closed state interface`);
      fields.navigation = {
        kind: "object-ref",
        expectation: { kind: "interface", interfaceRevisionId: state.target.interfaceRevisionId },
      };
    }
    if (!Array.isArray(declaration.inputs)) throw Error(`${name}: inputs must be an array of query bindings`);
    const steps = declaration.inputs.map((value) => {
      const step = object(value, `${name} input`) as unknown as QueryCompositionStep;
      if (step.name === "children") throw Error(`${name}: children is reserved for prepared child inputs`);
      const query = pkg.queries?.find((entry) => entry.displayName === step.query);
      if (!query) throw Error(`${name}.${step.name}: unknown query ${step.query}`);
      if (query.placement?.kind !== "local" && !query.fragment)
        throw Error(`${name}.${step.name}: requires a local projection or fragment`);
      return { ...step, query: query.id };
    });
    const composition = `react:inputs:${module.id}`;
    compositions.push({
      id: composition,
      input: { kind: "record", fields },
      steps,
      maxQueries: steps.reduce((count, step) => count + (step.each?.limit ?? 1), 0) || 1,
    });
    const children = declaration.children ?? [];
    if (!Array.isArray(children)) throw Error(`${name}: children must be an array`);
    const names = new Set<string>();
    const parsed = children.map((value) => {
      const child = object(value, `${name} child`) as unknown as ReactChildDeclaration;
      if (!child.name || names.has(child.name) || !child.slot || !child.root)
        throw Error(`${name}: child requires a unique name, slot and root`);
      names.add(child.name);
      // A local module identifies a closed role, including its generic arguments.
      // This avoids inventing an import alias for a generic application solely
      // to select that role in the React preparation manifest.
      let role: ReactChildDeclaration["role"];
      if (child.role) {
        const authored = object(child.role, `${name}.${child.name} role`);
        if (typeof authored.module === "string") {
          const target = pkg.modules?.find((entry) => entry.displayName === authored.module);
          if (!target || Object.keys(authored).length !== 1)
            throw Error(`${name}.${child.name}: expected a local module role`);
          role = { interface: target.interfaceRevisionId, member: target.memberId };
        } else {
          role = { ...child.role, interface: imported(child.role.interface) };
        }
      }
      if (child.each && child.with) throw Error(`${name}.${child.name}: cannot combine each and with`);
      if (child.each && (!Number.isSafeInteger(child.each.limit) || child.each.limit < 1))
        throw Error(`${name}.${child.name}: finite positive collection limit required`);
      return {
        ...child,
        subject: imported(child.subject),
        ...(role ? { role } : {}),
      };
    });
    const trees = declaration.trees ?? [];
    if (!Array.isArray(trees) || trees.length > 16) throw Error(`${name}: trees must be a bounded array`);
    const treeNames = new Set<string>();
    const preparedTrees = trees.map((value) => {
      const tree = object(value, `${name} tree`) as unknown as NonNullable<ReactModulePreparation["trees"]>[number];
      if (
        Object.keys(tree).some((key) => !["name", "query", "root", "arguments"].includes(key)) ||
        !/^[A-Za-z_][A-Za-z0-9_]*$/.test(tree.name) ||
        treeNames.has(tree.name)
      )
        throw Error(`${name}: tree requires a unique name and checked root/arguments`);
      treeNames.add(tree.name);
      const query = pkg.queries?.find((entry) => entry.displayName === tree.query);
      if (!query || query.placement?.kind !== "replica")
        throw Error(`${name}.${tree.name}: requires a replica Query Tree`);
      return { ...tree, query: query.id };
    });
    artifact.modules.push({
      module: module.id,
      composition,
      children: parsed,
      ...(preparedTrees.length ? { trees: preparedTrees } : {}),
    });
  }
  for (const module of pkg.modules ?? []) {
    const contract = interfaces.find((entry) => entry.revisionId === module.interfaceRevisionId);
    const member = contract?.members.find((entry) => entry.id === module.memberId);
    if (
      member?.kind === "module" &&
      member.contract.startsWith("org.quixos.react.") &&
      !artifact.modules.some((entry) => entry.module === module.id)
    )
      throw Error(`React module ${module.displayName} has no preparation declaration`);
  }
  return { compositions, artifact };
}