import { isObject, isString } from '@sindresorhus/is';
import type { SkipReason } from '../../../types/index.ts';
import type { ConstraintName } from '../../../util/exec/types.ts';
import { DartDatasource } from '../../datasource/dart/index.ts';
import { DartVersionDatasource } from '../../datasource/dart-version/index.ts';
import { FlutterVersionDatasource } from '../../datasource/flutter-version/index.ts';
import { GitRefsDatasource } from '../../datasource/git-refs/index.ts';
import type { PackageDependency, PackageFileContent } from '../types.ts';
import type { Pubspec } from './schema.ts';
import { parsePubspec } from './utils.ts';

function extractFromSection(
  pubspec: Pubspec,
  sectionKey: keyof Pick<Pubspec, 'dependencies' | 'dev_dependencies'>,
): PackageDependency[] {
  const sectionContent = pubspec[sectionKey];
  if (!sectionContent) {
    return [];
  }

  const skippedPackages = [
    'flutter_driver',
    'flutter_localizations',
    'flutter_test',
    'flutter_web_plugins',
    'meta',
  ];
  const deps: PackageDependency[] = [];
  for (const depName of Object.keys(sectionContent)) {
    if (skippedPackages.includes(depName)) {
      continue;
    }

    let currentValue = sectionContent[depName];
    let skipReason: SkipReason | undefined;
    let registryUrls: string[] | undefined;
    let gitUrl: string | undefined;

    if (!isString(currentValue)) {
      const version = currentValue.version;
      const path = currentValue.path;
      const hosted = currentValue.hosted;
      const git = currentValue.git;

      if (isString(hosted)) {
        registryUrls = [hosted];
      } else if (isString(hosted?.url)) {
        registryUrls = [hosted.url];
      }

      if (isObject(git)) {
        gitUrl = git?.url;
      } else if (isString(git)) {
        gitUrl = git;
      }

      if (version) {
        currentValue = version;
      } else if (path) {
        currentValue = '';
        skipReason = 'path-dependency';
      } else if (isObject(git) && isString(git?.ref)) {
        currentValue = git.ref;
      } else if (isObject(git) && !isString(git?.ref) && !isString(version)) {
        currentValue = '';
        skipReason = 'unspecified-version';
      } else {
        currentValue = '';
      }
    }

    if (gitUrl === undefined) {
      deps.push({
        depName,
        depType: sectionKey,
        currentValue,
        datasource: DartDatasource.id,
        ...(registryUrls && { registryUrls }),
        skipReason,
      });
    } else {
      deps.push({
        depName,
        depType: sectionKey,
        packageName: gitUrl,
        datasource: GitRefsDatasource.id,
        currentValue,
        skipReason,
      });
    }
  }

  return deps;
}

function extractDart(pubspec: Pubspec): PackageDependency[] {
  return [
    {
      depName: 'dart',
      currentValue: pubspec.environment.sdk,
      datasource: DartVersionDatasource.id,
    },
  ];
}

function extractFlutter(pubspec: Pubspec): PackageDependency[] {
  const currentValue = pubspec.environment.flutter;
  if (!currentValue) {
    return [];
  }

  return [
    {
      depName: 'flutter',
      currentValue,
      datasource: FlutterVersionDatasource.id,
    },
  ];
}

function extractConstraints(
  pubspec: Pubspec,
): Partial<Record<ConstraintName, string>> {
  const extractedConstraints: Partial<Record<ConstraintName, string>> = {
    // environment.sdk is a required field in a pubspec
    dart: pubspec.environment.sdk,
  };

  if (pubspec.environment.flutter) {
    extractedConstraints.flutter = pubspec.environment.flutter;
  }

  return extractedConstraints;
}

export function extractPackageFile(
  content: string,
  packageFile: string,
): PackageFileContent | null {
  const pubspec = parsePubspec(packageFile, content);
  if (!pubspec) {
    return null;
  }

  return {
    deps: [
      ...extractFromSection(pubspec, 'dependencies'),
      ...extractFromSection(pubspec, 'dev_dependencies'),
      ...extractDart(pubspec),
      ...extractFlutter(pubspec),
    ],
    extractedConstraints: extractConstraints(pubspec),
  };
}