import {
  isArray,
  isNumber,
  isPlainObject,
  isPrimitive,
  isString,
} from '@sindresorhus/is';
import handlebars, { type HelperOptions } from 'handlebars';
import { GlobalConfig } from '../../config/global.ts';
import { pkg } from '../../expose.ts';
import { logger } from '../../logger/index.ts';
import { toArray } from '../array.ts';
import { getChildEnv } from '../exec/utils.ts';
import { regEx } from '../regex.ts';

// Missing in handlebars
type Options = HelperOptions & {
  lookupProperty: (element: unknown, key: unknown) => unknown;
};

const helpers: Record<string, handlebars.HelperDelegate> = {
  encodeURIComponent,
  decodeURIComponent,
  encodeBase64: (str: string) => Buffer.from(str ?? '').toString('base64'),
  decodeBase64: (str: string) => Buffer.from(str ?? '', 'base64').toString(),
  stringToPrettyJSON: (input: string): string =>
    JSON.stringify(JSON.parse(input), null, 2),
  toJSON: (input: unknown): string => JSON.stringify(input),
  toArray: (...args: unknown[]): unknown[] => {
    // Need to remove the 'options', as the last parameter
    // https://handlebarsjs.com/api-reference/helpers.html
    args.pop();
    return args;
  },
  toObject: (...args: unknown[]): unknown => {
    // Need to remove the 'options', as the last parameter
    // https://handlebarsjs.com/api-reference/helpers.html
    args.pop();

    if (args.length % 2 !== 0) {
      throw new Error(`Must contain an even number of elements`);
    }

    const keys = args.filter((_, index) => index % 2 === 0);
    const values = args.filter((_, index) => index % 2 === 1);

    return Object.fromEntries(keys.map((key, index) => [key, values[index]]));
  },
  replace: (find, replace, context) =>
    (context ?? '').replace(regEx(find, 'g'), replace),
  lowercase: (str: string) => str?.toLowerCase(),
  containsString: (str, subStr) => str?.includes(subStr),
  equals: (arg1, arg2) => arg1 === arg2,
  includes: (arg1: string[], arg2: string) => {
    if (isArray(arg1, isString) && isString(arg2)) {
      return arg1.includes(arg2);
    }
    return false;
  },
  split: (str: unknown, separator: unknown): string[] => {
    if (isString(str) && isString(separator)) {
      return str.split(separator);
    }
    return [];
  },
  and: (...args: unknown[]) => {
    // Need to remove the 'options', as the last parameter
    // https://handlebarsjs.com/api-reference/helpers.html
    args.pop();
    return args.every(Boolean);
  },
  or: (...args: unknown[]) => {
    // Need to remove the 'options', as the last parameter
    // https://handlebarsjs.com/api-reference/helpers.html
    args.pop();
    return args.some(Boolean);
  },
  lookupArray: (obj: unknown, key: unknown, options: Options): unknown[] => {
    return (
      toArray(obj)
        // skip elements like #with does
        .filter((element) => !handlebars.Utils.isEmpty(element))
        .map((element) => options.lookupProperty(element, key))
        .filter((value) => value !== undefined)
    );
  },
  distinct: (obj: unknown): unknown[] => {
    const seen = new Set<string>();

    return toArray(obj).filter((value) => {
      const str = JSON.stringify(value);

      if (seen.has(str)) {
        return false;
      }

      seen.add(str);
      return true;
    });
  },
  add: (a, b) => {
    if (isNumber(a) && isNumber(b)) {
      return a + b;
    }

    throw new Error('add: inputs are not valid');
  },
};

// Register all helpers from the single source of truth
for (const [name, fn] of Object.entries(helpers)) {
  handlebars.registerHelper(name, fn);
}

// Export helper names derived from the same source used to register them
export const templateHelperNames = Object.keys(helpers) as readonly string[];

/**
 * Config options whose **values** are exposed as template variables.
 * e.g. `groupName` is in this list because you can write `{{groupName}}` inside a template.
 * This is distinct from `supportsTemplating`, which marks options whose values
 * are themselves *compiled* as Handlebars templates via `template.compile()`.
 */
export const exposedConfigOptions = [
  'additionalBranchPrefix',
  'addLabels',
  'allowedVersions',
  'branchName',
  'branchPrefix',
  'branchTopic',
  'commitBody',
  'commitMessage',
  'commitMessageAction',
  'commitMessageExtra',
  'commitMessagePrefix',
  'commitMessageSuffix',
  'commitMessageTopic',
  'gitAuthor',
  'group',
  'groupName',
  'groupSlug',
  'labels',
  'prBodyColumns',
  'prBodyDefinitions',
  'prBodyNotes',
  'prTitle',
  'semanticCommitScope',
  'semanticCommitType',
  'separateMajorMinor',
  'separateMinorPatch',
  'separateMultipleMinor',
  'sourceDirectory',
];

/**
 * Runtime-generated fields available as template variables.
 * These are not config options — they are computed during Renovate's run
 * (e.g. `depName`, `newVersion`, `isMajor`) and made available in templates.
 */
export const allowedFields = {
  baseBranch: 'The baseBranch for this branch/PR',
  body: 'The body of the release notes',
  categories: 'The categories of the manager of the dependency being updated',
  currentValue: 'The extracted current value of the dependency being updated',
  currentVersion:
    'The version that would be currently installed. For example, if currentValue is ^3.0.0 then currentVersion might be 3.1.0.',
  currentVersionAgeInDays: 'The age of the current version in days',
  currentVersionTimestamp: 'The timestamp of the current version',
  currentDigest: 'The extracted current digest of the dependency being updated',
  currentDigestShort:
    'The extracted current short digest of the dependency being updated',
  datasource: 'The datasource used to look up the upgrade',
  depName: 'The name of the dependency being updated',
  depNameLinked:
    'The dependency name already linked to its home page using markdown',
  depNameSanitized:
    'The depName field sanitized for use in branches after removing spaces and special characters',
  depType: 'The dependency type (if extracted - manager-dependent)',
  depTypes:
    'A deduplicated array of dependency types (if extracted - manager-dependent) in a branch',
  displayFrom: 'The current value, formatted for display',
  displayPending: 'Latest pending update, if internalChecksFilter is in use',
  displayTo: 'The to value, formatted for display',
  hasReleaseNotes: 'true if the upgrade has release notes',
  indentation: 'The indentation of the dependency being updated',
  isGroup: 'true if the upgrade is part of a group',
  isLockfileUpdate: 'true if the branch is a lock file update',
  isMajor: 'true if the upgrade is major',
  isMinor: 'true if the upgrade is minor',
  isPatch: 'true if the upgrade is a patch upgrade',
  isPin: 'true if the upgrade is pinning dependencies',
  isPinDigest: 'true if the upgrade is pinning digests',
  isRollback: 'true if the upgrade is a rollback PR',
  isReplacement: 'true if the upgrade is a replacement',
  isRange: 'true if the new value is a range',
  isSingleVersion:
    'true if the upgrade is to a single version rather than a range',
  isVulnerabilityAlert: 'true if the upgrade is a vulnerability alert',
  logJSON: 'ChangeLogResult object for the upgrade',
  manager: 'The (package) manager which detected the dependency',
  newDigest: 'The new digest value',
  newDigestShort:
    'A shortened version of newDigest, for use when the full digest is too long to be conveniently displayed',
  newMajor:
    'The major version of the new version. e.g. "3" if the new version is "3.1.0"',
  newMinor:
    'The minor version of the new version. e.g. "1" if the new version is "3.1.0"',
  newPatch:
    'The patch version of the new version. e.g. "0" if the new version is "3.1.0"',
  newName:
    'The name of the new dependency that replaces the current deprecated dependency',
  newNameLinked:
    'The new dependency name already linked to its home page using markdown',
  newValue:
    'The new value in the upgrade. Can be a range or version e.g. "^3.0.0" or "3.1.0"',
  newVersion: 'The new version in the upgrade, e.g. "3.1.0"',
  newVersionAgeInDays: 'The age of the new version in days',
  major:
    'The major version of the current version. e.g. "3" if the current version is "3.1.0"',
  minor:
    'The minor version of the current version. e.g. "1" if the current version is "3.1.0"',
  patch:
    'The patch version of the current version. e.g. "0" if the current version is "3.1.0"',
  packageFile: 'The filename that the dependency was found in',
  packageFileDir:
    'The directory with full path where the packageFile was found',
  packageName: 'The full name that was used to look up the dependency',
  packageScope: 'The scope of the package name. Supports Maven group ID only',
  parentDir:
    'The name of the directory that the dependency was found in, without full path',
  parentOrg: 'The name of the parent organization for the current repository',
  platform: 'VCS platform in use, e.g. "github", "gitlab", etc.',
  prettyDepType: 'Massaged depType',
  prettyNewMajor: 'The new major value with v prepended to it.',
  prettyNewVersion: 'The new version value with v prepended to it.',
  project: 'ChangeLogProject object',
  recreateClosed: 'If true, this PR will be recreated if closed',
  references: 'A list of references for the upgrade',
  releases: 'An array of releases for an upgrade',
  releaseNotes: 'A ChangeLogNotes object for the release',
  releaseTimestamp: 'The timestamp of the release',
  renovateVersion: 'The currently running Renovate version.',
  repository: 'The current repository',
  semanticPrefix: 'The fully generated semantic prefix for commit messages',
  sourceRepo: 'The repository in the sourceUrl, if present',
  sourceRepoName: 'The repository name in the sourceUrl, if present',
  sourceRepoOrg: 'The repository organization in the sourceUrl, if present',
  sourceRepoSlug: 'The slugified pathname of the sourceUrl, if present',
  sourceUrl: 'The source URL for the package',
  topLevelOrg:
    'The name of the top-level organization for the current repository',
  updateType:
    'One of digest, pin, rollback, patch, minor, major, replacement, pinDigest',
  upgrades: 'An array of upgrade objects in the branch',
  url: 'The url of the release notes',
  version: 'The version number of the changelog',
  versioning: 'The versioning scheme in use',
  versions: 'An array of ChangeLogRelease objects in the upgrade',
  vulnerabilitySeverity:
    'The severity for a vulnerability alert upgrade (LOW, MEDIUM, MODERATE, HIGH, CRITICAL, UNKNOWN)',
};

type CompileInput<T = Record<string, unknown>> = T;

/**
 * The complete set of field names that may be referenced inside a Handlebars template.
 * Union of runtime fields (`allowedFields`) and config options (`exposedConfigOptions`).
 * Used by the compile proxy to warn on unknown variable references.
 */
const allowedTemplateFields = new Set([
  ...Object.keys(allowedFields),
  ...exposedConfigOptions,
]);

class CompileInputProxyHandler implements ProxyHandler<CompileInput> {
  private warnVariables: Set<string>;

  constructor(warnVariables: Set<string>) {
    this.warnVariables = warnVariables;
  }

  get(target: CompileInput, prop: keyof CompileInput): unknown {
    if (prop === 'env') {
      return target[prop];
    }

    if (!allowedTemplateFields.has(prop)) {
      this.warnVariables.add(prop);
      return undefined;
    }

    const value = target[prop];

    if (prop === 'prBodyDefinitions') {
      // Expose all prBodyDefinitions.*
      return value;
    }

    if (isArray(value)) {
      return value.map((element) =>
        isPrimitive(element)
          ? element
          : proxyCompileInput(element as CompileInput, this.warnVariables),
      );
    }

    if (isPlainObject(value)) {
      return proxyCompileInput(value, this.warnVariables);
    }

    return value;
  }
}

export function proxyCompileInput(
  input: CompileInput,
  warnVariables: Set<string>,
): CompileInput {
  return new Proxy<CompileInput>(
    input,
    new CompileInputProxyHandler(warnVariables),
  );
}

export function compile<T>(
  template: string,
  input: CompileInput<T>,
  filterFields = true,
): string {
  const env = getChildEnv({});
  const data = {
    ...GlobalConfig.get(),
    renovateVersion: pkg.version,
    ...input,
    env,
  };
  const warnVariables = new Set<string>();
  const filteredInput = filterFields
    ? proxyCompileInput(data, warnVariables)
    : data;

  logger.trace({ template, filteredInput }, 'Compiling template');
  const result = handlebars.compile(template, { noEscape: true })(
    filteredInput,
  );

  if (warnVariables.size > 0) {
    logger.info(
      { varNames: Array.from(warnVariables), template },
      'Disallowed variable names in template',
    );
  }

  return result;
}

export function safeCompile<T>(
  template: string,
  input: CompileInput<T>,
  filterFields = true,
): string {
  try {
    return compile(template, input, filterFields);
  } catch (err) {
    logger.warn({ err, template }, 'Error compiling template');
    return '';
  }
}

/**
 * Validate that the template is a valid Handlebars template string.
 *
 * NOTE: Does not validate that fields are set to valid field names.
 */
export function validate(template: string): void {
  handlebars.parse(template);
}