import { createHash } from "node:crypto";
import { Buffer } from "node:buffer";
import type { FastifyInstance, FastifyReply, FastifyRequest } from "fastify";
import multipart from "@fastify/multipart";
import yauzl from "yauzl";
import yazl from "yazl";
import { z } from "zod";
import type { WorkspaceRegistryConfig } from "../workspaces/types.js";
import { WorkspaceRegistryError } from "../workspaces/git-repository.js";
import {
  WorkspaceConflictError,
  type PublishWorkspaceRequest,
  type WorkspaceRegistry,
} from "../workspaces/registry.js";
import { resolveRuntimeBindings } from "../workspaces/bindings.js";
import { buildInstallationContract, renderWorkspaceDocs } from "../workspaces/contracts.js";
import {
  parseWorkspaceYaml,
  serializeWorkspaceYaml,
  validateOperationalWorkspace,
  validateWorkspaceDescriptor,
  type CanonicalWorkspace,
  type WorkspaceDescriptor,
} from "../workspaces/schema.js";
import type { RuntimeBindings } from "../workspaces/runtime-renderer.js";
import type { WorkspaceDiagnostics } from "../workspaces/diagnostics.js";

export type WorkspaceDiagnoser = (
  workspace: WorkspaceDescriptor,
  bindings: RuntimeBindings,
  options: { writeProbe: boolean },
) => Promise<WorkspaceDiagnostics>;

interface WorkspaceRoutesDeps {
  registry: WorkspaceRegistry;
  config: WorkspaceRegistryConfig;
  diagnose: WorkspaceDiagnoser;
}

const workspaceId = z.string().regex(/^[a-z][a-z0-9-]{2,62}$/);
const commit = z.string().regex(/^[0-9a-f]{40}$/);
const workspacePayload = z.object({ workspace: z.unknown() }).strict();
const publishPayload = z.discriminatedUnion("action", [
  z.object({ action: z.literal("create"), workspace: z.unknown(), baseCommit: commit }).strict(),
  z.object({ action: z.literal("update"), workspace: z.unknown(), baseCommit: commit, baseBlob: commit }).strict(),
  z.object({ action: z.literal("delete"), id: workspaceId, baseCommit: commit, baseBlob: commit }).strict(),
]);
const bundleManifest = z.object({
  schema_version: z.literal(1),
  workspace_id: workspaceId,
  files: z.object({
    "workspace.yaml": z.string().regex(/^[0-9a-f]{64}$/),
    "contract.env.example": z.string().regex(/^[0-9a-f]{64}$/),
    "README.md": z.string().regex(/^[0-9a-f]{64}$/),
  }).strict(),
}).strict();

// Public P1 bundles contain only the descriptor and derived docs. Evidence file bytes remain
// revision-owned Git content for the later P6 materialization boundary.
const BUNDLE_FILES = ["manifest.json", "workspace.yaml", "contract.env.example", "README.md"] as const;
type BundleFile = (typeof BUNDLE_FILES)[number];

const SAFE_MESSAGES = {
  workspace_invalid: "Workspace request or bundle is invalid.",
  binding_missing: "Installation binding is missing or invalid.",
  workspace_not_activatable: "Workspace cannot be activated on this installation.",
  workspace_stale: "Workspace revision is stale.",
  workspace_conflict: "Workspace changed in the registry.",
  workspace_curator_owned: "Workspace descriptor is owned by the curator and must be changed through Git.",
  git_unavailable: "Workspace Git service is unavailable.",
  git_auth_failed: "Workspace Git authentication failed.",
  git_non_fast_forward: "Workspace Git branch has changed.",
  git_push_rejected: "Workspace Git publication was rejected.",
  connector_unavailable: "Workspace connector is unavailable.",
  semantic_index_incompatible: "Semantic index is incompatible with this workspace.",
} as const;

function sha256(value: string | Buffer): string {
  return createHash("sha256").update(value).digest("hex");
}

function invalidBundle(): WorkspaceRegistryError {
  return new WorkspaceRegistryError("workspace_invalid", "Workspace bundle is invalid");
}

function isBundleFile(value: string): value is BundleFile {
  return (BUNDLE_FILES as readonly string[]).includes(value);
}

function unsafeArchiveEntry(entry: yauzl.Entry): boolean {
  const name = entry.fileName;
  const unixType = (entry.externalFileAttributes >>> 16) & 0o170000;
  return name.length === 0
    || name.startsWith("/")
    || name.startsWith("\\")
    || name.includes("\\")
    || name.split("/").includes("..")
    || name.endsWith("/")
    || unixType === 0o120000
    || !isBundleFile(name);
}

async function readZipBundle(source: Buffer, config: WorkspaceRegistryConfig): Promise<Record<BundleFile, Buffer>> {
  if (source.length === 0 || source.length > config.maxImportBytes) throw invalidBundle();
  return await new Promise<Record<BundleFile, Buffer>>((resolve, reject) => {
    yauzl.fromBuffer(source, {
      lazyEntries: true,
      strictFileNames: true,
      validateEntrySizes: true,
      decodeStrings: true,
    }, (error, archive) => {
      if (error || !archive) return reject(invalidBundle());
      const files = new Map<BundleFile, Buffer>();
      let entries = 0;
      let settled = false;
      const fail = () => {
        if (settled) return;
        settled = true;
        archive.close();
        reject(invalidBundle());
      };
      archive.on("error", fail);
      archive.on("entry", (entry) => {
        entries += 1;
        if (entries > config.maxImportEntries || unsafeArchiveEntry(entry) || files.has(entry.fileName as BundleFile)) {
          fail();
          return;
        }
        if (entry.uncompressedSize > config.maxImportBytes) {
          fail();
          return;
        }
        archive.openReadStream(entry, (streamError, stream) => {
          if (streamError || !stream) return fail();
          const chunks: Buffer[] = [];
          let size = 0;
          stream.on("data", (chunk: Buffer) => {
            size += chunk.length;
            if (size > config.maxImportBytes) return fail();
            chunks.push(chunk);
          });
          stream.on("error", fail);
          stream.on("end", () => {
            if (settled || size !== entry.uncompressedSize) return fail();
            files.set(entry.fileName as BundleFile, Buffer.concat(chunks));
            archive.readEntry();
          });
        });
      });
      archive.on("end", () => {
        if (settled) return;
        settled = true;
        if (entries !== BUNDLE_FILES.length || BUNDLE_FILES.some((name) => !files.has(name))) return reject(invalidBundle());
        resolve(Object.fromEntries(files) as Record<BundleFile, Buffer>);
      });
      archive.readEntry();
    });
  });
}

function utf8(buffer: Buffer): string {
  const text = buffer.toString("utf8");
  if (!Buffer.from(text, "utf8").equals(buffer) || text.includes("\0")) throw invalidBundle();
  return text;
}

async function importDraft(source: Buffer, config: WorkspaceRegistryConfig): Promise<CanonicalWorkspace> {
  const files = await readZipBundle(source, config);
  let manifest: z.infer<typeof bundleManifest>;
  try {
    manifest = bundleManifest.parse(JSON.parse(utf8(files["manifest.json"])));
  } catch {
    throw invalidBundle();
  }
  for (const name of ["workspace.yaml", "contract.env.example", "README.md"] as const) {
    if (sha256(files[name]) !== manifest.files[name]) throw invalidBundle();
  }
  try {
    const descriptor = parseWorkspaceYaml(utf8(files["workspace.yaml"]));
    const workspace = validateWorkspaceDescriptor(descriptor);
    const docs = renderWorkspaceDocs(workspace);
    if (
      workspace.workspace.id !== manifest.workspace_id
      || serializeWorkspaceYaml(workspace) !== utf8(files["workspace.yaml"])
      || docs.envExample !== utf8(files["contract.env.example"])
      || docs.markdown !== utf8(files["README.md"])
    ) throw invalidBundle();
    return workspace;
  } catch (error) {
    if (error instanceof WorkspaceRegistryError) throw error;
    throw invalidBundle();
  }
}

async function exportBundle(workspace: CanonicalWorkspace): Promise<Buffer> {
  const yaml = serializeWorkspaceYaml(workspace);
  const docs = renderWorkspaceDocs(workspace);
  const files: Record<BundleFile, string> = {
    "manifest.json": JSON.stringify({
      schema_version: 1,
      workspace_id: workspace.workspace.id,
      files: {
        "workspace.yaml": sha256(yaml),
        "contract.env.example": sha256(docs.envExample),
        "README.md": sha256(docs.markdown),
      },
    }),
    "workspace.yaml": yaml,
    "contract.env.example": docs.envExample,
    "README.md": docs.markdown,
  };
  const archive = new yazl.ZipFile();
  const chunks: Buffer[] = [];
  archive.outputStream.on("data", (chunk: Buffer) => chunks.push(chunk));
  for (const name of BUNDLE_FILES) archive.addBuffer(Buffer.from(files[name]), name);
  archive.end();
  await new Promise<void>((resolve, reject) => {
    archive.outputStream.once("end", resolve);
    archive.outputStream.once("error", reject);
  });
  return Buffer.concat(chunks);
}

function workspaceErrorCode(error: unknown): keyof typeof SAFE_MESSAGES {
  return error instanceof WorkspaceRegistryError ? error.code : "workspace_invalid";
}

function workspaceErrorStatus(code: keyof typeof SAFE_MESSAGES): number {
  if (code === "workspace_conflict" || code === "workspace_curator_owned" || code === "workspace_stale" || code === "git_non_fast_forward") return 409;
  if (code === "git_unavailable" || code === "git_auth_failed" || code === "git_push_rejected") return 503;
  return 400;
}

function validatedWorkspace(value: unknown): WorkspaceDescriptor | undefined {
  try {
    return validateWorkspaceDescriptor(value);
  } catch {
    return undefined;
  }
}

function errorReply(reply: FastifyReply, error: unknown) {
  const code = workspaceErrorCode(error);
  const body: Record<string, unknown> = { code, message: SAFE_MESSAGES[code] };
  if (error instanceof WorkspaceConflictError) {
    body.fields = error.fields;
    body.expected = error.expected;
    body.actual = error.actual;
    if (error.base) body.base = error.base;
    if (error.local) body.local = error.local;
    if (error.remote) body.remote = error.remote;
  } else if (code === "workspace_conflict" && error && typeof error === "object") {
    const conflict = error as Partial<WorkspaceConflictError>;
    if (Array.isArray(conflict.fields) && conflict.fields.every((field) => typeof field === "string")) body.fields = conflict.fields;
    for (const key of ["expected", "actual"] as const) {
      const revision = conflict[key];
      if (
        revision
        && typeof revision.commit === "string" && /^[0-9a-f]{40}$/.test(revision.commit)
        && (revision.blob === undefined || (typeof revision.blob === "string" && /^[0-9a-f]{40}$/.test(revision.blob)))
      ) body[key] = revision;
    }
    for (const key of ["base", "local", "remote"] as const) {
      const workspace = validatedWorkspace(conflict[key]);
      if (workspace) body[key] = workspace;
    }
  }
  return reply.code(workspaceErrorStatus(code)).send(body);
}

function publishRequest(value: unknown): PublishWorkspaceRequest {
  const parsed = publishPayload.parse(value);
  if (parsed.action === "delete") return parsed;
  return { ...parsed, workspace: validateWorkspaceDescriptor(parsed.workspace) };
}

export function workspaceRoutes(app: FastifyInstance, deps: WorkspaceRoutesDeps): void {
  app.register(multipart, {
    limits: { fileSize: deps.config.maxImportBytes, files: 1, fields: 0, parts: 1 },
    throwFileSizeLimit: true,
  });

  app.get("/workspace-registry/status", async (_request, reply) => {
    try {
      return await deps.registry.bootstrap();
    } catch (error) {
      return errorReply(reply, error);
    }
  });

  app.post("/workspace-registry/pull", async (_request, reply) => {
    try {
      return await deps.registry.pull();
    } catch (error) {
      return errorReply(reply, error);
    }
  });

  app.get("/workspaces", async (_request, reply) => {
    try {
      const records = await deps.registry.listCatalog();
      return records.map((record) => ({
        id: record.id,
        // Retain the metadata endpoint's selector field while adding catalog metadata.
        name: record.id,
        file: `${record.id}/workspace.yaml`,
        displayName: record.name,
        description: record.description,
        configurationState: record.configurationState,
        ...(record.revision ? { revision: record.revision } : {}),
      }));
    } catch (error) {
      return errorReply(reply, error);
    }
  });

  app.get("/workspaces/:id", async (request, reply) => {
    try {
      const { id } = z.object({ id: workspaceId }).parse(request.params);
      return await deps.registry.read(id);
    } catch (error) {
      return errorReply(reply, error);
    }
  });

  app.post("/workspaces/validate", async (request, reply) => {
    try {
      const { workspace } = workspacePayload.parse(request.body);
      const canonical = validateWorkspaceDescriptor(workspace);
      return { workspace: canonical, contract: buildInstallationContract(canonical) };
    } catch (error) {
      return errorReply(reply, error);
    }
  });

  app.post("/workspaces/:id/test", async (request, reply) => {
    try {
      const { id } = z.object({ id: workspaceId }).parse(request.params);
      const { workspace } = await deps.registry.read(id);
      let operational: CanonicalWorkspace;
      try {
        operational = validateOperationalWorkspace(workspace);
      } catch {
        throw new WorkspaceRegistryError(
          "workspace_not_activatable", "Workspace requires explicit migration",
        );
      }
      const bindings = resolveRuntimeBindings(operational, process.env, deps.config.secretRoots);
      return await deps.diagnose(operational, bindings, { writeProbe: false });
    } catch (error) {
      return errorReply(reply, error);
    }
  });

  app.post("/workspaces/publish", async (request, reply) => {
    try {
      const result = await deps.registry.publish(publishRequest(request.body));
      return result ? { revision: result } : reply.code(204).send();
    } catch (error) {
      return errorReply(reply, error);
    }
  });

  app.get("/workspaces/:id/export", async (request, reply) => {
    try {
      const { id } = z.object({ id: workspaceId }).parse(request.params);
      const { workspace } = await deps.registry.read(id);
      const canonical = validateWorkspaceDescriptor(workspace);
      const bundle = await exportBundle(canonical);
      return reply
        .type("application/zip")
        .header("content-disposition", `attachment; filename=\"${id}.zip\"`)
        .send(bundle);
    } catch (error) {
      return errorReply(reply, error);
    }
  });

  app.post("/workspaces/import", async (request: FastifyRequest, reply) => {
    try {
      const file = await request.file();
      if (!file || file.fieldname !== "bundle" || file.mimetype !== "application/zip") throw invalidBundle();
      const draft = await importDraft(await file.toBuffer(), deps.config);
      return { draft: { workspace: draft, contract: buildInstallationContract(draft) } };
    } catch (error) {
      return errorReply(reply, error);
    }
  });
}