import fs from 'node:fs/promises';
import path from 'node:path';
import {
  assertNoProhibitedBrowserStorage,
} from './mindspace-browser-storage-policy.mjs';
import {
  buildMindSpacePublicUrlForUser,
  resolveMindSpaceUserPublishDir,
} from './mindspace-runtime-config.mjs';
import {
  renderLongImage,
} from './mindspace-long-image.mjs';
import {
  UPLOAD_ZONE_CODES,
} from './user-space.mjs';

function workspaceToolError(message, code) {
  return Object.assign(new Error(message), { code });
}

function requireServiceMethod(
  service,
  methodName,
) {
  if (
    !service ||
    typeof service[methodName] !== 'function'
  ) {
    throw new Error(
      `createMindSpaceWorkspaceToolService requires conversationArtifactService.${methodName}`,
    );
  }
}

function requiredString(value, field) {
  const normalized = String(value ?? '').trim();
  if (!normalized) {
    throw workspaceToolError(
      `${field} is required`,
      'invalid_workspace_tool_input',
    );
  }
  return normalized;
}

export function parseMindSpaceWorkspaceRef(
  workspaceRef,
) {
  const normalized = requiredString(
    workspaceRef,
    'workspaceRef',
  );
  let parsed;
  try {
    parsed = new URL(normalized);
  } catch {
    throw workspaceToolError(
      'Invalid MindSpace workspaceRef',
      'invalid_workspace_ref',
    );
  }
  let segments;
  try {
    segments = parsed.pathname
      .split('/')
      .filter(Boolean)
      .map((segment) =>
        decodeURIComponent(segment),
      );
  } catch {
    throw workspaceToolError(
      'Invalid MindSpace workspaceRef encoding',
      'invalid_workspace_ref',
    );
  }
  if (
    parsed.protocol !== 'mindspace:' ||
    parsed.hostname !== 'users' ||
    parsed.username ||
    parsed.password ||
    parsed.port ||
    parsed.search ||
    parsed.hash ||
    segments.length !== 2 ||
    segments[1] !== 'workspace' ||
    segments[0] === '.' ||
    segments[0] === '..' ||
    /[\\/]/.test(segments[0])
  ) {
    throw workspaceToolError(
      'Invalid MindSpace workspaceRef',
      'invalid_workspace_ref',
    );
  }
  return {
    workspaceRef: normalized,
    userId: requiredString(
      segments[0],
      'workspaceRef.userId',
    ),
  };
}

export function normalizeMindSpaceWorkspacePath(
  value,
  { allowRoot = false } = {},
) {
  const raw = String(value ?? '')
    .normalize('NFKC')
    .trim()
    .replace(/\\/g, '/');
  if (
    (allowRoot && (!raw || raw === '.')) ||
    (allowRoot && raw === './')
  ) {
    return '';
  }
  if (
    !raw ||
    raw.startsWith('/') ||
    /^[a-z]:\//i.test(raw) ||
    raw.includes('\0')
  ) {
    throw workspaceToolError(
      'Workspace path must be relative',
      'invalid_workspace_path',
    );
  }
  const segments = raw
    .split('/')
    .filter(Boolean);
  if (
    segments.some(
      (segment) =>
        segment === '.' ||
        segment === '..',
    ) ||
    segments[0] === '.mindspace'
  ) {
    throw workspaceToolError(
      'Workspace path is outside the allowed logical workspace',
      'invalid_workspace_path',
    );
  }
  return segments.join('/');
}

function pathInsideRoot(root, target) {
  return (
    target === root ||
    target.startsWith(`${root}${path.sep}`)
  );
}

async function ensureNoSymlinkTraversal(
  root,
  relativePath,
  { includeLeaf = true } = {},
) {
  const rootReal = await fs.realpath(root);
  const segments = relativePath
    ? relativePath.split('/')
    : [];
  const limit = includeLeaf
    ? segments.length
    : Math.max(0, segments.length - 1);
  let current = rootReal;
  for (let index = 0; index < limit; index += 1) {
    current = path.join(
      current,
      segments[index],
    );
    let stat;
    try {
      stat = await fs.lstat(current);
    } catch (error) {
      if (error?.code === 'ENOENT') break;
      throw error;
    }
    if (stat.isSymbolicLink()) {
      throw workspaceToolError(
        'Workspace symlink traversal is forbidden',
        'invalid_workspace_path',
      );
    }
  }
  return rootReal;
}

async function resolveExistingWorkspacePath(
  root,
  relativePath,
) {
  const rootReal =
    await ensureNoSymlinkTraversal(
      root,
      relativePath,
    );
  const target = path.join(
    rootReal,
    ...relativePath.split('/'),
  );
  let targetReal;
  try {
    targetReal = await fs.realpath(target);
  } catch (error) {
    if (error?.code === 'ENOENT') {
      throw workspaceToolError(
        `Workspace entry not found: ${relativePath}`,
        'workspace_entry_not_found',
      );
    }
    throw error;
  }
  if (!pathInsideRoot(rootReal, targetReal)) {
    throw workspaceToolError(
      'Workspace path escaped its logical root',
      'invalid_workspace_path',
    );
  }
  return targetReal;
}

async function resolveWritableWorkspacePath(
  root,
  relativePath,
) {
  const rootReal =
    await ensureNoSymlinkTraversal(
      root,
      relativePath,
      { includeLeaf: false },
    );
  const target = path.join(
    rootReal,
    ...relativePath.split('/'),
  );
  await fs.mkdir(path.dirname(target), {
    recursive: true,
  });
  const parentReal = await fs.realpath(
    path.dirname(target),
  );
  if (!pathInsideRoot(rootReal, parentReal)) {
    throw workspaceToolError(
      'Workspace path escaped its logical root',
      'invalid_workspace_path',
    );
  }
  try {
    const stat = await fs.lstat(target);
    if (stat.isSymbolicLink()) {
      throw workspaceToolError(
        'Workspace symlink writes are forbidden',
        'invalid_workspace_path',
      );
    }
  } catch (error) {
    if (error?.code !== 'ENOENT') throw error;
  }
  return target;
}

function assertPackageScope(
  sessionId,
  packageId,
) {
  const expected = `cp_${sessionId}`;
  if (packageId !== expected) {
    throw workspaceToolError(
      'packageId does not match the scoped session',
      'invalid_workspace_package_scope',
    );
  }
}

function mimeSafeByteLength(content) {
  return Buffer.byteLength(
    String(content ?? ''),
    'utf8',
  );
}

function decodeWorkspaceBinary(
  value,
  { maxBytes },
) {
  const encoded = String(value ?? '').trim();
  if (
    !encoded ||
    encoded.length % 4 !== 0 ||
    !/^[A-Za-z0-9+/]*={0,2}$/.test(encoded)
  ) {
    throw workspaceToolError(
      'Workspace binary body must be valid base64',
      'invalid_workspace_binary',
    );
  }
  const body = Buffer.from(encoded, 'base64');
  if (
    body.length === 0 ||
    body.length > maxBytes ||
    body.toString('base64') !== encoded
  ) {
    throw workspaceToolError(
      body.length > maxBytes
        ? 'Workspace binary file exceeds the write limit'
        : 'Workspace binary body must be valid base64',
      body.length > maxBytes
        ? 'workspace_file_too_large'
        : 'invalid_workspace_binary',
    );
  }
  return body;
}

export function createMindSpaceWorkspaceToolService({
  h5Root,
  env = process.env,
  syncWorkspaceAssets = null,
  conversationArtifactService,
  workspacePageDeliveryService = null,
  resolveMindSpaceUserPublishDirFn =
    resolveMindSpaceUserPublishDir,
  buildMindSpacePublicUrlForUserFn =
    buildMindSpacePublicUrlForUser,
  renderLongImageFn = renderLongImage,
  maxReadBytes = 5 * 1024 * 1024,
  maxWriteBytes = 10 * 1024 * 1024,
  maxBinaryWriteBytes = 8 * 1024 * 1024,
  maxGeneratedBinaryBytes =
    40 * 1024 * 1024,
} = {}) {
  if (!h5Root) {
    throw new Error(
      'createMindSpaceWorkspaceToolService requires h5Root',
    );
  }
  requireServiceMethod(
    conversationArtifactService,
    'registerPublicHtmlArtifacts',
  );
  requireServiceMethod(
    conversationArtifactService,
    'registerWorkspaceFileArtifact',
  );
  if (
    !workspacePageDeliveryService ||
    typeof workspacePageDeliveryService
      .syncAndDeliver !== 'function'
  ) {
    throw new Error(
      'createMindSpaceWorkspaceToolService requires workspacePageDeliveryService.syncAndDeliver',
    );
  }

  const resolveScope = (input = {}) => {
    const {
      workspaceRef,
      sessionId,
      packageId,
    } = input;
    const parsed =
      parseMindSpaceWorkspaceRef(workspaceRef);
    const suppliedUserId = String(
      input.userId ?? '',
    ).trim();
    if (
      suppliedUserId &&
      suppliedUserId !== parsed.userId
    ) {
      throw workspaceToolError(
        'userId does not match workspaceRef',
        'invalid_workspace_user_scope',
      );
    }
    const normalizedSessionId =
      requiredString(sessionId, 'sessionId');
    const normalizedPackageId =
      requiredString(packageId, 'packageId');
    assertPackageScope(
      normalizedSessionId,
      normalizedPackageId,
    );
    const workspaceRoot =
      resolveMindSpaceUserPublishDirFn(
        h5Root,
        { id: parsed.userId },
      );
    return {
      ...parsed,
      sessionId: normalizedSessionId,
      packageId: normalizedPackageId,
      workspaceRoot,
    };
  };

  const registerWrite = async ({
    scope,
    relativePath,
    messageId = null,
    body = null,
  }) => {
    let publicHtmlArtifacts = [];
    let workspaceFileArtifact = null;
    if (
      relativePath.startsWith('public/') &&
      relativePath.toLowerCase().endsWith('.html') &&
      typeof conversationArtifactService
        ?.registerPublicHtmlArtifacts ===
        'function'
    ) {
      publicHtmlArtifacts =
        await conversationArtifactService
          .registerPublicHtmlArtifacts({
            userId: scope.userId,
            sessionId: scope.sessionId,
            relativePaths: [relativePath],
            artifactRefs: [
              {
                relativePath,
                messageId:
                  String(messageId ?? '').trim() ||
                  null,
              },
            ],
          });
    } else if (
      body != null &&
      typeof conversationArtifactService
        ?.registerWorkspaceFileArtifact ===
        'function'
    ) {
      workspaceFileArtifact =
        await conversationArtifactService
          .registerWorkspaceFileArtifact({
            userId: scope.userId,
            sessionId: scope.sessionId,
            messageId:
              String(messageId ?? '').trim() ||
              null,
            relativePath,
            body,
          });
    }
    const categoryCode =
      relativePath.split('/')[0];
    let assetSync = null;
    if (
      typeof syncWorkspaceAssets === 'function' &&
      UPLOAD_ZONE_CODES.includes(categoryCode)
    ) {
      assetSync = await syncWorkspaceAssets(
        scope.userId,
        {
          categoryCode,
          onlyRelativePaths: [relativePath],
        },
      );
    }
    return {
      assetSync,
      publicHtmlArtifacts,
      workspaceFileArtifact,
    };
  };

  return {
    async readFile(input = {}) {
      const scope = resolveScope(input);
      const relativePath =
        normalizeMindSpaceWorkspacePath(
          input.path,
        );
      const target =
        await resolveExistingWorkspacePath(
          scope.workspaceRoot,
          relativePath,
        );
      const stat = await fs.stat(target);
      if (!stat.isFile()) {
        throw workspaceToolError(
          'Workspace path is not a file',
          'invalid_workspace_path',
        );
      }
      if (stat.size > maxReadBytes) {
        throw workspaceToolError(
          'Workspace file exceeds the read limit',
          'workspace_file_too_large',
        );
      }
      return {
        workspaceRef: scope.workspaceRef,
        packageId: scope.packageId,
        relativePath,
        content: await fs.readFile(
          target,
          'utf8',
        ),
        sizeBytes: stat.size,
      };
    },

    async writeFile(input = {}) {
      const scope = resolveScope(input);
      const relativePath =
        normalizeMindSpaceWorkspacePath(
          input.path,
        );
      const content = String(
        input.content ?? '',
      );
      const sizeBytes =
        mimeSafeByteLength(content);
      if (sizeBytes > maxWriteBytes) {
        throw workspaceToolError(
          'Workspace file exceeds the write limit',
          'workspace_file_too_large',
        );
      }
      assertNoProhibitedBrowserStorage(
        content,
        { relativePath },
      );
      const target =
        await resolveWritableWorkspacePath(
          scope.workspaceRoot,
          relativePath,
        );
      await fs.writeFile(target, content, 'utf8');
      const registration = await registerWrite({
        scope,
        relativePath,
        messageId: input.messageId,
        body: content,
      });
      return {
        workspaceRef: scope.workspaceRef,
        packageId: scope.packageId,
        relativePath,
        sizeBytes,
        registration,
      };
    },

    async writeBinaryFile(input = {}) {
      const scope = resolveScope(input);
      const relativePath =
        normalizeMindSpaceWorkspacePath(
          input.path,
        );
      const body = decodeWorkspaceBinary(
        input.bodyBase64,
        { maxBytes: maxBinaryWriteBytes },
      );
      const target =
        await resolveWritableWorkspacePath(
          scope.workspaceRoot,
          relativePath,
        );
      await fs.writeFile(target, body);
      const registration = await registerWrite({
        scope,
        relativePath,
        messageId: input.messageId,
        body,
      });
      return {
        workspaceRef: scope.workspaceRef,
        packageId: scope.packageId,
        relativePath,
        sizeBytes: body.length,
        registration,
      };
    },

    async editFile(input = {}) {
      const scope = resolveScope(input);
      const relativePath =
        normalizeMindSpaceWorkspacePath(
          input.path,
        );
      const target =
        await resolveExistingWorkspacePath(
          scope.workspaceRoot,
          relativePath,
        );
      const original = await fs.readFile(
        target,
        'utf8',
      );
      const oldString = String(
        input.oldString ?? input.old_str ?? '',
      );
      if (
        oldString &&
        !original.includes(oldString)
      ) {
        throw workspaceToolError(
          'edit_file: old_str was not found',
          'workspace_edit_not_found',
        );
      }
      const newString = String(
        input.newString ?? input.new_str ?? '',
      );
      const updated = oldString
        ? original.replace(oldString, newString)
        : newString;
      const sizeBytes =
        mimeSafeByteLength(updated);
      if (sizeBytes > maxWriteBytes) {
        throw workspaceToolError(
          'Workspace file exceeds the write limit',
          'workspace_file_too_large',
        );
      }
      assertNoProhibitedBrowserStorage(
        updated,
        { relativePath },
      );
      await fs.writeFile(target, updated, 'utf8');
      const registration = await registerWrite({
        scope,
        relativePath,
        messageId: input.messageId,
        body: updated,
      });
      return {
        workspaceRef: scope.workspaceRef,
        packageId: scope.packageId,
        relativePath,
        sizeBytes,
        registration,
      };
    },

    async listDirectory(input = {}) {
      const scope = resolveScope(input);
      const relativePath =
        normalizeMindSpaceWorkspacePath(
          input.path,
          { allowRoot: true },
        );
      const target = relativePath
        ? await resolveExistingWorkspacePath(
            scope.workspaceRoot,
            relativePath,
          )
        : await fs.realpath(
            scope.workspaceRoot,
          );
      const entries = await fs.readdir(target, {
        withFileTypes: true,
      });
      return {
        workspaceRef: scope.workspaceRef,
        packageId: scope.packageId,
        relativePath,
        entries: entries
          .filter(
            (entry) =>
              entry.name !== '.mindspace',
          )
          .map((entry) => ({
            name: entry.name,
            type: entry.isDirectory()
              ? 'directory'
              : entry.isFile()
                ? 'file'
                : 'other',
          }))
          .sort((left, right) =>
            left.name.localeCompare(right.name),
          ),
      };
    },

    async createDirectory(input = {}) {
      const scope = resolveScope(input);
      const relativePath =
        normalizeMindSpaceWorkspacePath(
          input.path,
        );
      const target =
        await resolveWritableWorkspacePath(
          scope.workspaceRoot,
          `${relativePath}/.mindspace-create-placeholder`,
        );
      await fs.mkdir(path.dirname(target), {
        recursive: true,
      });
      return {
        workspaceRef: scope.workspaceRef,
        packageId: scope.packageId,
        relativePath,
      };
    },

    async generateLongImage(input = {}) {
      const scope = resolveScope(input);
      const htmlRelativePath =
        normalizeMindSpaceWorkspacePath(
          input.htmlPath ??
            input.html_path ??
            input.path,
        );
      if (
        !htmlRelativePath
          .toLowerCase()
          .endsWith('.html')
      ) {
        throw workspaceToolError(
          'generate_long_image requires an HTML source',
          'invalid_workspace_page_path',
        );
      }
      const outputRelativePath =
        normalizeMindSpaceWorkspacePath(
          input.outputPath ??
            input.output_path ??
            htmlRelativePath.replace(
              /\.html$/i,
              '.long.png',
            ),
        );
      if (
        !outputRelativePath
          .toLowerCase()
          .endsWith('.png')
      ) {
        throw workspaceToolError(
          'generate_long_image output must be PNG',
          'invalid_workspace_binary',
        );
      }
      const htmlTarget =
        await resolveExistingWorkspacePath(
          scope.workspaceRoot,
          htmlRelativePath,
        );
      const htmlStat = await fs.stat(htmlTarget);
      if (!htmlStat.isFile()) {
        throw workspaceToolError(
          'Long-image source is not a file',
          'invalid_workspace_path',
        );
      }
      const outputTarget =
        await resolveWritableWorkspacePath(
          scope.workspaceRoot,
          outputRelativePath,
        );
      const sourceCanonicalUrl =
        buildMindSpacePublicUrlForUserFn({
          h5Root,
          env,
          user: {
            id: scope.userId,
          },
          relativePath:
            htmlRelativePath,
        });
      await renderLongImageFn({
        url: sourceCanonicalUrl,
        outputPath: outputTarget,
      });
      const outputStat =
        await fs.stat(outputTarget);
      if (
        !outputStat.isFile() ||
        outputStat.size <= 0
      ) {
        throw workspaceToolError(
          'Long-image renderer did not produce a file',
          'workspace_entry_not_found',
        );
      }
      if (
        outputStat.size >
        maxGeneratedBinaryBytes
      ) {
        throw workspaceToolError(
          'Generated long image exceeds the write limit',
          'workspace_file_too_large',
        );
      }
      const registration = await registerWrite({
        scope,
        relativePath: outputRelativePath,
        messageId: input.messageId,
        body: await fs.readFile(outputTarget),
      });
      return {
        workspaceRef: scope.workspaceRef,
        packageId: scope.packageId,
        relativePath: outputRelativePath,
        sizeBytes: outputStat.size,
        sourceCanonicalUrl,
        canonicalUrl:
          outputRelativePath.startsWith(
            'public/',
          )
            ? buildMindSpacePublicUrlForUserFn({
                h5Root,
                env,
                user: {
                  id: scope.userId,
                },
                relativePath:
                  outputRelativePath,
              })
            : null,
        registration,
      };
    },

    async publishPage(input = {}) {
      const scope = resolveScope(input);
      const relativePath =
        normalizeMindSpaceWorkspacePath(
          input.path ?? input.relativePath,
        );
      if (
        !relativePath.startsWith('public/') ||
        !relativePath.toLowerCase().endsWith('.html')
      ) {
        throw workspaceToolError(
          'publish_page requires public/*.html',
          'invalid_workspace_page_path',
        );
      }
      await resolveExistingWorkspacePath(
        scope.workspaceRoot,
        relativePath,
      );
      const registration = await registerWrite({
        scope,
        relativePath,
        messageId: input.messageId,
      });
      const delivery =
        await workspacePageDeliveryService
          .syncAndDeliver(scope.userId, {
            pageDataRelativePaths: [
              relativePath,
            ],
          });
      return {
        workspaceRef: scope.workspaceRef,
        packageId: scope.packageId,
        relativePath,
        canonicalUrl:
          buildMindSpacePublicUrlForUserFn({
            h5Root,
            env,
            user: { id: scope.userId },
            relativePath,
          }),
        registration,
        delivery,
      };
    },
  };
}

export const mindSpaceWorkspaceToolServiceInternals = {
  assertPackageScope,
  decodeWorkspaceBinary,
  ensureNoSymlinkTraversal,
  requireServiceMethod,
  resolveExistingWorkspacePath,
  resolveWritableWorkspacePath,
};