import fs from "node:fs/promises";
import path from "node:path";
import { contentDigest } from "../capability-model/evolution.js";
import {
  validateMigrationCatalog,
  type MigrationCatalog,
  type MigrationDeclaration,
} from "../capability-model/migrations.js";
import { formatQuixosLock, type GitSource } from "../resource-lock/index.js";
import { parseQx, walkSyntax } from "./source.js";
import type { StructuralRequest } from "./structural-plan.js";
import { addImplementation } from "./implementation-edit.js";
import { reactPlatformTypes } from "../bindings/react-platform.js";

type Source = { repository: string; commit: string };
type PackageEditModel = {
  generatedBy: "qx-scaffold-v1";
  name: string;
  id: string;
  revision: string;
  exports: { name: string; id: string; file: string; migration?: boolean }[];
};
export type ScaffoldRecipe = {
  template?: "typescript" | "typescript-react";
  source: Source;
  directory?: string;
  name?: string;
  id?: string;
  revision?: string;
  declaration?: string;
  /** Initial authored files for a composed recipe; only used for a new package. */
  initialFiles?: Record<string, string>;
  tools?: { quixos: Source; protocol: Source; helpers: Source; sdk: Source };
  nixifyPluginUrl?: string;
  migration?: Omit<MigrationDeclaration, "implementation"> & { contracts: Record<string, unknown> };
};
const json = (value: unknown) => `${JSON.stringify(value, null, 2)}\n`;
const source = (value: Source): GitSource => {
  if (!value || typeof value.repository !== "string" || typeof value.commit !== "string")
    throw new Error("Scaffold requires an exact source identity; use qx-workspace from a registered repository");
  const url = new URL(value.repository);
  if (
    url.protocol !== "https:" ||
    url.username ||
    url.password ||
    url.search ||
    url.hash ||
    !/^(?:[0-9a-f]{40}|[0-9a-f]{64})$/.test(value.commit)
  )
    throw new Error("Scaffolds require credential-free HTTPS sources and full exact commits");
  return { resolver: "git", ...value };
};
const nixSource = (value: Source) =>
  `git+${source(value).repository}?ref=refs/tags/quixos-reachability/${value.commit}&rev=${value.commit}`;
const nixString = (value: string) => JSON.stringify(value).replaceAll("${", "\\${");
const safeName = (name: string | undefined): string => {
  if (!name || !/^[A-Za-z_][A-Za-z0-9_]*$/.test(name)) throw new Error("Scaffold requires a simple authored name");
  return name;
};
const ownedJson = async <T>(root: string, file: string): Promise<T> => {
  const target = path.join(root, file);
  if (!(await fs.realpath(target)).startsWith(`${await fs.realpath(root)}/`))
    throw new Error("Scaffold input escapes repository");
  const value = JSON.parse(await fs.readFile(target, "utf8"));
  if (value.generatedBy !== "qx-scaffold-v1") throw new Error(`Not scaffold-owned: ${file}`);
  return value;
};

/** Recipes describe structural edits; planStructure owns validation/journaling.
 * Implementation files are created once; later edits preserve authored wiring. */
export const scaffoldRecipe = async (
  root: string,
  command: "package" | "function" | "migration" | "refresh",
  spec: ScaffoldRecipe,
): Promise<StructuralRequest> => {
  if (command === "refresh")
    throw new Error(
      "Scaffold refresh has been removed. Edit declarations and typed server wiring directly, then run qx-workspace check. Use scaffold function to add a declaration and handler together.",
    );
  source(spec.source);
  if (spec.directory && !/^[A-Za-z0-9_-][A-Za-z0-9_.-]*(?:\/[A-Za-z0-9_-][A-Za-z0-9_.-]*)*$/.test(spec.directory))
    throw new Error("Scaffold directory must be contained");
  const prefix = spec.directory ? `${spec.directory}/` : "";
  const files: StructuralRequest["files"] = [];
  const create = (file: string, content: string) => files.push({ file: prefix + file, create: content });
  const generated = (file: string, content: string) => files.push({ file: prefix + file, generated: content });
  let packageModel: PackageEditModel;
  let catalog: MigrationCatalog & { generatedBy: "qx-scaffold-v1" };
  if (command === "package") {
    const name = safeName(spec.name);
    if (spec.template && !["typescript", "typescript-react"].includes(spec.template))
      throw new Error("Unknown package template");
    const react = spec.template === "typescript-react";
    if (!spec.id || !spec.revision || !spec.tools)
      throw new Error("Package scaffold requires id, revision, and exact quixos/protocol/helpers/sdk tool sources");
    Object.values(spec.tools).forEach(source);
    packageModel = { generatedBy: "qx-scaffold-v1", name, id: spec.id, revision: spec.revision, exports: [] };
    catalog = { generatedBy: "qx-scaffold-v1", schemaVersion: 1, contracts: {}, migrations: [] };
    if (react)
      packageModel.exports.push({ name: "sourceGet", id: `export:${name}:source`, file: "src/impl/sourceGet.ts" });
    create(
      "package.qx",
      `package ${name} id ${JSON.stringify(spec.id)} revision ${JSON.stringify(spec.revision)} {\n${react ? `  function sourceGet id ${JSON.stringify(`export:${name}:source`)} : unit -> string;\n` : ""}}\n`,
    );
    create("quixos.lock", formatQuixosLock({ formatVersion: 1, quixos: source(spec.tools.quixos), resources: [] }));
    create(
      "package.json",
      json({
        name: `@quixos/${name.toLowerCase()}`,
        version: "0.1.0",
        private: true,
        type: "module",
        packageManager: "yarn@4.18.0",
        scripts: { build: "tsc -p tsconfig.json", typecheck: "tsc --noEmit" },
        dependencies: {
          "@quixos/camino-package-runtime": `${spec.tools.sdk.repository}#commit=${spec.tools.sdk.commit}`,
        },
        devDependencies: {
          "@types/node": "^24",
          typescript: "^7.0.2",
          ...(react ? { react: "^18.3.1", "@types/react": "^18.3.12", esbuild: "^0.25.12" } : {}),
        },
      }),
    );
    create(
      "tsconfig.json",
      json({
        compilerOptions: {
          target: "ES2023",
          module: "NodeNext",
          moduleResolution: "NodeNext",
          strict: true,
          types: ["node", ...(react ? ["react"] : [])],
          outDir: "dist",
          rootDir: "src",
          skipLibCheck: true,
          ...(react ? { jsx: "react-jsx", esModuleInterop: true } : {}),
        },
        include: ["src/**/*.ts", "src/**/*.tsx"],
      }),
    );
    if (react) {
      create(
        "src/component.tsx",
        `// Add a checked props export, select it in quixos.check.json options.react,\n// then use its generated ReactResults type. Scaffold bundle does this for you.\nexport default function Component(_props: {camino: Record<string, never>; render: unknown; dispatch: (action: unknown) => void}) {\n  return <section><h1>${name}</h1></section>;\n}\n`,
      );
      create(
        "src/impl/sourceGet.ts",
        `import componentSource from "../component.js?browser-source";\nimport type {Implementation} from "../gen/qx.js";\nexport const handler: Implementation["sourceGet"] = () => componentSource;\n`,
      );
      create(
        "src/browser-assets.d.ts",
        `declare module "*?browser-source" { const source: string; export default source; }\ndeclare module "*.css" {}\n`,
      );
      create("src/gen/web-studio-react-runtime.d.ts", reactPlatformTypes);
    }
    create(".gitignore", "node_modules/\ndist/\n.quixos/\nresult\n.yarn/install-state.gz\n");
    create(
      ".yarnrc.yml",
      `nodeLinker: node-modules\nenableScripts: true\nnpmMinimalAgeGate: 0\napprovedGitRepositories:\n  - ${JSON.stringify(spec.tools.sdk.repository)}\nsupportedArchitectures:\n  os: [current, linux]\n  cpu: [current, x64, arm64]\n  libc: [current, glibc]\n`,
    );
    const nixifyPluginUrl =
      spec.nixifyPluginUrl ??
      "https://gitea-external.egads.tutti.syntaxblitz.net/quixos/yarn-plugin-nixify-patched/raw/commit/4528fdd20b30d869262443b3f044549810e75fb8/dist/yarn-plugin-nixify.js";
    const plugin = new URL(nixifyPluginUrl);
    if (
      plugin.protocol !== "https:" ||
      plugin.username ||
      plugin.password ||
      plugin.search ||
      plugin.hash ||
      !/\/commit\/[a-f0-9]{40,64}\//.test(plugin.pathname)
    )
      throw new Error("Nixify plugin must have an exact credential-free HTTPS commit URL");
    generated("quixos.toolchain.json", json({ generatedBy: "qx-scaffold-v1", nixifyPluginUrl }));
    create(
      "quixos.check.json",
      json({
        backend: "typescript",
        bindingOutput: "src/gen/qx.ts",
        ...(react
          ? {
              options: { react: { propsExports: [] } },
            }
          : {}),
      }),
    );
    create(
      "flake.nix",
      `{
  inputs.protocol.url = ${nixString(nixSource(spec.tools.protocol))};
  inputs.nixpkgs.follows = "protocol/nixpkgs";
  inputs.flake-utils.follows = "protocol/flake-utils";
  inputs.helpers = { url = ${nixString(nixSource(spec.tools.helpers))}; flake = false; };
  outputs = inputs@{ self, protocol, nixpkgs, flake-utils, helpers, ... }:
    (import (toString helpers + "/quixos-package-helpers.nix")).mkCaminoTsYarnNixifyFlake {
      inherit inputs nixpkgs flake-utils; packageRoot = ./.;
      bundle = { entry = ${JSON.stringify(react ? "src/server.ts" : "dist/server.js")}; ${react ? "browserSources = true;" : ""} };
      migrationEntrypoint = "dist/migrate.js";
      installServer = { libexecName = ${JSON.stringify(name.toLowerCase())}; descriptorPath = "descriptor.quixos-package.txtpb"; };
    };
}\n`,
    );
  } else {
    catalog = await ownedJson<typeof catalog>(root, prefix + "quixos.migrations.json");
    // Derive the edit model from authored declarations; it is never persisted.
    const authored = await fs.readFile(path.join(root, prefix, "package.qx"), "utf8");
    const syntax = parseQx(authored);
    if (syntax.diagnostics.length)
      throw new Error("Cannot scaffold into an invalid package.qx; fix the reported syntax first");
    const declaration = [...walkSyntax(syntax.root)].find((node) => node.kind === "packageResourceDecl");
    if (!declaration) throw new Error("Expected a package declaration");
    const text = (node: typeof declaration) => authored.slice(node.start, node.end);
    const literals = declaration.children.filter((node) => node.kind === "stringLiteral");
    packageModel = {
      generatedBy: "qx-scaffold-v1",
      name: text(declaration.children.find((node) => node.kind === "identifier")!),
      id: JSON.parse(text(literals[0])),
      revision: JSON.parse(text(literals[1])),
      exports: [],
    };
    for (const node of walkSyntax(declaration)) {
      if (!["packageFunctionExport", "packageOperationExport", "packageConstructorExport"].includes(node.kind))
        continue;
      const name = safeName(text(node.children.find((child) => child.kind === "identifier")!));
      const id = JSON.parse(text(node.children.find((child) => child.kind === "stringLiteral")!));
      if (packageModel.exports.some((entry) => entry.id === id || entry.name === name))
        throw new Error("Duplicate package export name or ID");
      const migration = catalog.migrations.find((entry) => entry.implementation.exportId === id);
      packageModel.exports.push({
        name,
        id,
        file: migration?.implementation.file ?? `src/impl/${name}.ts`,
        ...(migration ? { migration: true } : {}),
      });
    }
    {
      const name = safeName(spec.name);
      if (!spec.id || packageModel.exports.some((entry) => entry.id === spec.id || entry.name === name))
        throw new Error("New export requires a unique name and ID");
      const declaration = spec.declaration ?? `function ${name} id ${JSON.stringify(spec.id)} : unit -> unit;`;
      const parsed = parseQx(`package Scaffold id "scaffold" revision "scaffold@1" { ${declaration} }`);
      const exports = [...walkSyntax(parsed.root)].filter((node) =>
        ["packageFunctionExport", "packageOperationExport", "packageConstructorExport"].includes(node.kind),
      );
      if (parsed.diagnostics.length || exports.length !== 1)
        throw new Error("Expected one valid package export declaration");
      const wrapped = `package Scaffold id "scaffold" revision "scaffold@1" { ${declaration} }`;
      const node = exports[0];
      const derived = [...walkSyntax(node)].some((entry) => entry.kind === "eventClause");
      if (command === "migration" && (node.kind !== "packageFunctionExport" || spec.declaration))
        throw new Error(
          "Migration exports use the scaffold's unit function declaration and dedicated migration entrypoint",
        );
      if (
        wrapped.slice(
          node.children.find((child) => child.kind === "identifier")!.start,
          node.children.find((child) => child.kind === "identifier")!.end,
        ) !== name ||
        JSON.parse(
          wrapped.slice(
            node.children.find((child) => child.kind === "stringLiteral")!.start,
            node.children.find((child) => child.kind === "stringLiteral")!.end,
          ),
        ) !== spec.id
      )
        throw new Error("Declaration name/ID must match its registration");
      files.push({
        file: prefix + "package.qx",
        edits: [
          { operation: "append", parent: { kind: "packageResourceDecl", id: packageModel.id }, source: declaration },
        ],
      });
      const file = `src/${command === "migration" ? "migrations" : "impl"}/${name}.ts`;
      const implementation =
        command === "migration"
          ? `import type {MigrationContext} from "@quixos/camino-package-runtime";\nexport const handler = async (_context: MigrationContext): Promise<void> => { throw new Error(${JSON.stringify(`Implement migration ${name}`)}); };\n`
          : `import type {Implementation} from "../gen/qx.js";\nexport const handler: Implementation[${JSON.stringify(name)}] = ${derived ? '{kind: "derived", get: ' : ""}async (_context) => { throw new Error(${JSON.stringify(`Implement ${name}`)}); }${derived ? "}" : ""};\n`;
      create(file, implementation);
      packageModel.exports.push({ name, id: spec.id, file, ...(command === "migration" ? { migration: true } : {}) });
      if (command === "migration") {
        if (!spec.migration)
          throw new Error("Migration scaffold requires retained contracts and an explicit transition");
        const { contracts, ...transition } = spec.migration;
        for (const [digest, contract] of Object.entries(contracts)) {
          if (
            contentDigest(contract) !== digest ||
            (catalog.contracts[digest] && contentDigest(catalog.contracts[digest]) !== digest)
          )
            throw new Error("Retained migration contract mismatch");
          catalog.contracts[digest] = contract;
        }
        catalog.migrations.push({
          ...transition,
          implementation: { exportId: spec.id, file, digest: contentDigest(implementation) },
        });
      }
    }
  }
  validateMigrationCatalog(catalog, new Set(packageModel.exports.map((entry) => entry.id)));
  generated("quixos.migrations.json", json(catalog));
  if (command !== "package") {
    const entry = packageModel.exports.at(-1)!;
    const file = prefix + "src/server.ts";
    const before = await fs.readFile(path.join(root, file), "utf8");
    files.push({
      file,
      expected: before,
      replace: addImplementation(
        before,
        "createRuntime",
        entry.name,
        `./${entry.file.slice(4, -3)}.js`,
        !!entry.migration,
      ),
    });
    if (entry.migration) {
      const file = prefix + "src/migrate.ts";
      const before = await fs.readFile(path.join(root, file), "utf8");
      files.push({
        file,
        expected: before,
        replace: addImplementation(before, "serveMigration", entry.id, `./${entry.file.slice(4, -3)}.js`),
      });
    }
  } else {
    create(
      "src/server.ts",
      `import {servePackageRuntime} from "@quixos/camino-package-runtime";\nimport {createRuntime} from "./gen/qx.js";\n` +
        packageModel.exports
          .filter((entry) => !entry.migration)
          .map(
            (entry, index) =>
              `import {handler as impl${index}} from ${JSON.stringify(`./${entry.file.slice(4, -3)}.js`)};\n`,
          )
          .join("") +
        `servePackageRuntime(createRuntime({\n` +
        packageModel.exports
          .map(
            (entry) =>
              `  ${JSON.stringify(entry.name)}: ${entry.migration ? 'async () => { throw new Error("Migration-only export"); }' : `impl${packageModel.exports.filter((value) => !value.migration).indexOf(entry)}`},`,
          )
          .join("\n") +
        `\n}));\n`,
    );
    const migrations = packageModel.exports.filter((entry) => entry.migration);
    create(
      "src/migrate.ts",
      `import {serveMigration} from "@quixos/camino-package-runtime";\n` +
        migrations
          .map(
            (entry, index) =>
              `import {handler as impl${index}} from ${JSON.stringify(`./${entry.file.slice(4, -3)}.js`)};\n`,
          )
          .join("") +
        `await serveMigration({${migrations.map((entry, index) => `${JSON.stringify(entry.id)}: impl${index}`).join(", ")}});\n`,
    );
  }
  generated(
    "descriptor.quixos-package.txtpb",
    `# Generated by qx-scaffold-v1\npackage_id: ${JSON.stringify(packageModel.id)}\npackage_revision_id: ${JSON.stringify(packageModel.revision)}\nruntime_protocol_version: "quixos-capabilities-v1"\n` +
      packageModel.exports
        .map(
          (entry) =>
            `exports: { export_id: ${JSON.stringify(entry.id)} runtime_symbol: ${JSON.stringify(entry.name)} }\n`,
        )
        .join(""),
  );
  if (spec.initialFiles) {
    if (command !== "package") throw new Error("initialFiles is only valid when creating a package");
    const authored = spec.initialFiles["package.qx"];
    if (authored !== undefined) {
      const parsed = parseQx(authored);
      const declaration = [...walkSyntax(parsed.root)].find((n) => n.kind === "packageResourceDecl");
      const literals = declaration?.children.filter((n) => n.kind === "stringLiteral") ?? [];
      const identifier = declaration?.children.find((n) => n.kind === "identifier");
      if (
        parsed.diagnostics.length ||
        literals.length !== 2 ||
        !identifier ||
        authored.slice(identifier.start, identifier.end) !== spec.name ||
        JSON.parse(authored.slice(literals[0].start, literals[0].end)) !== spec.id ||
        JSON.parse(authored.slice(literals[1].start, literals[1].end)) !== spec.revision
      )
        throw new Error("Initial package declaration must match the provisioned name, ID and revision");
    }
    for (const [file, content] of Object.entries(spec.initialFiles)) {
      if (
        typeof content !== "string" ||
        ["quixos.lock", "flake.nix", "quixos.toolchain.json", "package.json"].includes(file)
      )
        throw new Error(`Not an initial authored file: ${file}`);
      if (file === "quixos.check.json") {
        const check = JSON.parse(content);
        if (
          check.backend !== "typescript" ||
          check.bindingOutput !== "src/gen/qx.ts" ||
          Object.keys(check).some((key) => !["backend", "bindingOutput", "options"].includes(key))
        )
          throw new Error(
            "Initial check configuration may customize binding options, not the scaffold verification backend or output",
          );
      }
      const existing = files.findIndex((entry) => entry.file === prefix + file);
      if (existing >= 0) files.splice(existing, 1);
      create(file, content);
    }
    // A composed React recipe supplies its own modules and complete server.
    if (reactRecipe(spec)) {
      for (const file of ["src/component.tsx", "src/impl/sourceGet.ts", "descriptor.quixos-package.txtpb"])
        if (!(file in spec.initialFiles)) {
          const index = files.findIndex((entry) => entry.file === prefix + file);
          if (index >= 0) files.splice(index, 1);
        }
    }
  }
  return { kind: "package", source: spec.source, resourceRoot: spec.directory, validation: "syntax", files };
};

const reactRecipe = (spec: ScaffoldRecipe) =>
  spec.template === "typescript-react" && spec.initialFiles?.["package.qx"] && spec.initialFiles?.["src/server.ts"];