const BLOCKED_INSTALL_DEPENDENCY_PACKAGE_NAMES = ["plain-crypto-js"] as const;

export const blockedInstallDependencyPackageNames = [
  ...BLOCKED_INSTALL_DEPENDENCY_PACKAGE_NAMES,
] as const;

export type BlockedManifestDependencyFinding = {
  dependencyName: string;
  declaredAs?: string;
  field: "dependencies" | "name" | "optionalDependencies" | "overrides" | "peerDependencies";
};

export type BlockedPackageDirectoryFinding = {
  dependencyName: string;
  directoryRelativePath: string;
};

export type BlockedPackageFileFinding = {
  dependencyName: string;
  fileRelativePath: string;
};

type PackageDependencyMapFields = Partial<
  Record<
    Exclude<BlockedManifestDependencyFinding["field"], "name" | "overrides">,
    Record<string, string>
  >
>;

type PackageDependencyFields = {
  name?: string;
} & PackageDependencyMapFields;

interface PackageOverrideObject {
  [key: string]: PackageOverrideValue;
}

type PackageOverrideValue = string | PackageOverrideObject;

type PackageOverrideFields = {
  overrides?: unknown;
};

const BLOCKED_INSTALL_DEPENDENCY_PACKAGE_NAME_SET = new Set<string>(
  blockedInstallDependencyPackageNames,
);

const BLOCKED_INSTALL_DEPENDENCY_PACKAGE_NAME_LOWER_SET = new Set<string>(
  blockedInstallDependencyPackageNames.map((packageName) => packageName.toLowerCase()),
);

function isBlockedInstallDependencyPackageName(packageName: string): boolean {
  return BLOCKED_INSTALL_DEPENDENCY_PACKAGE_NAME_SET.has(packageName);
}

function isBlockedInstallDependencyPackagePathName(packageName: string): boolean {
  return BLOCKED_INSTALL_DEPENDENCY_PACKAGE_NAME_LOWER_SET.has(packageName.toLowerCase());
}

function normalizePathSegments(relativePath: string): string[] {
  return relativePath
    .split(/[\\/]+/)
    .map((segment) => segment.trim())
    .filter(Boolean);
}

function parseBlockedNodeModulesPackageId(
  segments: string[],
  packageNameSegmentTransform: (packageNameSegment: string) => string | undefined,
): string | undefined {
  for (let index = 0; index < segments.length; index += 1) {
    if (segments[index]?.toLowerCase() !== "node_modules") {
      continue;
    }
    const packageScopeOrName = segments[index + 1];
    if (!packageScopeOrName) {
      continue;
    }

    if (packageScopeOrName.startsWith("@")) {
      const packageNameSegment = segments[index + 2];
      if (!packageNameSegment) {
        continue;
      }
      const packageName = packageNameSegmentTransform(packageNameSegment);
      if (!packageName) {
        continue;
      }
      const scopedPackageId = `${packageScopeOrName}/${packageName}`;
      if (!isBlockedInstallDependencyPackagePathName(scopedPackageId)) {
        continue;
      }
      return scopedPackageId;
    }

    const packageName = packageNameSegmentTransform(packageScopeOrName);
    if (!packageName || !isBlockedInstallDependencyPackagePathName(packageName)) {
      continue;
    }
    return packageName;
  }

  return undefined;
}

function parseNpmAliasTargetPackageName(spec: string): string | undefined {
  const normalized = spec.trim();
  if (!normalized.startsWith("npm:")) {
    return undefined;
  }

  const aliasTarget = normalized.slice("npm:".length).trim();
  if (!aliasTarget) {
    return undefined;
  }

  if (aliasTarget.startsWith("@")) {
    const slashIndex = aliasTarget.indexOf("/");
    if (slashIndex < 0) {
      return undefined;
    }
    const versionSeparatorIndex = aliasTarget.indexOf("@", slashIndex + 1);
    return versionSeparatorIndex < 0 ? aliasTarget : aliasTarget.slice(0, versionSeparatorIndex);
  }

  const versionSeparatorIndex = aliasTarget.indexOf("@");
  return versionSeparatorIndex < 0 ? aliasTarget : aliasTarget.slice(0, versionSeparatorIndex);
}

function parsePackageNameFromOverrideSelector(selector: string): string | undefined {
  const normalized = selector.trim();
  if (!normalized || normalized === ".") {
    return undefined;
  }

  if (normalized.startsWith("@")) {
    const slashIndex = normalized.indexOf("/");
    if (slashIndex < 0) {
      return undefined;
    }
    const versionSeparatorIndex = normalized.indexOf("@", slashIndex + 1);
    return versionSeparatorIndex < 0 ? normalized : normalized.slice(0, versionSeparatorIndex);
  }

  const versionSeparatorIndex = normalized.indexOf("@");
  return versionSeparatorIndex < 0 ? normalized : normalized.slice(0, versionSeparatorIndex);
}

function collectBlockedOverrideFindings(
  value: PackageOverrideValue,
  path: string[] = [],
): BlockedManifestDependencyFinding[] {
  if (typeof value === "string") {
    const aliasTargetPackageName = parseNpmAliasTargetPackageName(value);
    if (!aliasTargetPackageName) {
      return [];
    }
    if (!BLOCKED_INSTALL_DEPENDENCY_PACKAGE_NAME_SET.has(aliasTargetPackageName)) {
      return [];
    }
    return [
      {
        dependencyName: aliasTargetPackageName,
        declaredAs: path.join(" > "),
        field: "overrides",
      },
    ];
  }

  const findings: BlockedManifestDependencyFinding[] = [];
  for (const overrideKey of Object.keys(value).toSorted()) {
    const overrideSelectorPackageName = parsePackageNameFromOverrideSelector(overrideKey);
    if (
      overrideSelectorPackageName &&
      BLOCKED_INSTALL_DEPENDENCY_PACKAGE_NAME_SET.has(overrideSelectorPackageName)
    ) {
      findings.push({
        dependencyName: overrideSelectorPackageName,
        declaredAs: [...path, overrideKey].join(" > "),
        field: "overrides",
      });
    }
    findings.push(...collectBlockedOverrideFindings(value[overrideKey], [...path, overrideKey]));
  }
  return findings;
}

function isPackageOverrideObject(value: unknown): value is PackageOverrideObject {
  return typeof value === "object" && value !== null && !Array.isArray(value);
}

export function findBlockedManifestDependencies(
  manifest: PackageDependencyFields & PackageOverrideFields,
): BlockedManifestDependencyFinding[] {
  const findings: BlockedManifestDependencyFinding[] = [];
  if (manifest.name && isBlockedInstallDependencyPackageName(manifest.name)) {
    findings.push({ dependencyName: manifest.name, field: "name" });
  }
  if (isPackageOverrideObject(manifest.overrides)) {
    findings.push(...collectBlockedOverrideFindings(manifest.overrides));
  }
  for (const field of ["dependencies", "optionalDependencies", "peerDependencies"] as const) {
    const dependencyMap = manifest[field];
    if (!dependencyMap) {
      continue;
    }
    for (const dependencyName of Object.keys(dependencyMap).toSorted()) {
      if (isBlockedInstallDependencyPackageName(dependencyName)) {
        findings.push({ dependencyName, field });
        continue;
      }

      const aliasTargetPackageName = parseNpmAliasTargetPackageName(dependencyMap[dependencyName]);
      if (!aliasTargetPackageName) {
        continue;
      }
      if (!isBlockedInstallDependencyPackageName(aliasTargetPackageName)) {
        continue;
      }
      findings.push({
        dependencyName: aliasTargetPackageName,
        declaredAs: dependencyName,
        field,
      });
    }
  }
  return findings;
}

export function findBlockedNodeModulesDirectory(params: {
  directoryRelativePath: string;
}): BlockedPackageDirectoryFinding | undefined {
  const dependencyName = parseBlockedNodeModulesPackageId(
    normalizePathSegments(params.directoryRelativePath),
    (packageNameSegment) => packageNameSegment,
  );
  return dependencyName
    ? {
        dependencyName,
        directoryRelativePath: params.directoryRelativePath,
      }
    : undefined;
}

function parseBlockedPackageFileAliasName(fileName: string): string | undefined {
  const extensionMatch = /^(.+)\.(js|json|node)$/i.exec(fileName);
  if (extensionMatch) {
    return extensionMatch[1];
  }
  if (fileName.includes(".")) {
    return undefined;
  }
  return fileName;
}

export function findBlockedNodeModulesFileAlias(params: {
  fileRelativePath: string;
}): BlockedPackageFileFinding | undefined {
  const dependencyName = parseBlockedNodeModulesPackageId(
    normalizePathSegments(params.fileRelativePath),
    parseBlockedPackageFileAliasName,
  );
  return dependencyName
    ? {
        dependencyName,
        fileRelativePath: params.fileRelativePath,
      }
    : undefined;
}

export function findBlockedPackageDirectoryInPath(params: {
  pathRelativeToRoot: string;
}): BlockedPackageDirectoryFinding | undefined {
  const segments = normalizePathSegments(params.pathRelativeToRoot);

  for (let index = 0; index < segments.length; index += 1) {
    const packageScopeOrName = segments[index];
    if (!packageScopeOrName) {
      continue;
    }

    if (packageScopeOrName.startsWith("@")) {
      const packageName = segments[index + 1];
      if (!packageName) {
        continue;
      }
      const scopedPackageId = `${packageScopeOrName}/${packageName}`;
      if (!isBlockedInstallDependencyPackagePathName(scopedPackageId)) {
        index += 1;
        continue;
      }
      return {
        dependencyName: scopedPackageId,
        directoryRelativePath: params.pathRelativeToRoot,
      };
    }

    if (!isBlockedInstallDependencyPackagePathName(packageScopeOrName)) {
      continue;
    }
    return {
      dependencyName: packageScopeOrName,
      directoryRelativePath: params.pathRelativeToRoot,
    };
  }

  return undefined;
}

export function findBlockedPackageFileAliasInPath(params: {
  pathRelativeToRoot: string;
}): BlockedPackageFileFinding | undefined {
  const segments = normalizePathSegments(params.pathRelativeToRoot);
  const fileName = segments.at(-1);
  if (!fileName) {
    return undefined;
  }
  const dependencyName = parseBlockedPackageFileAliasName(fileName);
  if (!dependencyName || !isBlockedInstallDependencyPackagePathName(dependencyName)) {
    return undefined;
  }
  return {
    dependencyName,
    fileRelativePath: params.pathRelativeToRoot,
  };
}