import {
  AST_NODE_TYPES,
  ESLintUtils,
  TSESLint,
  TSESTree,
} from '@typescript-eslint/utils';
import { Scope } from '@typescript-eslint/utils/ts-eslint';

import {
  DSpaceESLintRuleInfo,
  NamedTests,
  OptionDoc,
} from '../../util/structure';

export enum Message {
  MISSING_ALIAS = 'missingAlias',
  WRONG_ALIAS = 'wrongAlias',
  MULTIPLE_ALIASES = 'multipleAliases',
  UNNECESSARY_ALIAS = 'unnecessaryAlias',
}

interface AliasImportOptions {
  aliases: AliasImportOption[];
}

interface AliasImportOption {
  package: string;
  imported: string;
  local: string;
}

interface AliasImportDocOptions {
  aliases: OptionDoc;
}

export const info: DSpaceESLintRuleInfo<[AliasImportOptions], [AliasImportDocOptions]> = {
  name: 'alias-imports',
  meta: {
    docs: {
      description: 'Unclear imports should be aliased for clarity',
    },
    messages: {
      [Message.MISSING_ALIAS]: 'This import must be aliased',
      [Message.WRONG_ALIAS]: 'This import uses the wrong alias (should be {{ local }})',
      [Message.MULTIPLE_ALIASES]: 'This import was used twice with a different alias (should be {{ local }})',
      [Message.UNNECESSARY_ALIAS]: 'This import should not use an alias',
    },
    fixable: 'code',
    type: 'problem',
    schema: {
      type: 'array',
      items: {
        type: 'object',
        properties: {
          package: { type: 'string' },
          imported: { type: 'string' },
          local: { type: 'string' },
        },
      },
    },
  },
  optionDocs: [
    {
      aliases:  {
        title: '`aliases`',
        description: `A list of all the imports that you want to alias for clarity. Every alias should be declared in the following format:
\`\`\`json
{
  "package": "rxjs",
  "imported": "of",
  "local": "observableOf"
}
\`\`\``,
      },
    },
  ],
  defaultOptions: [
    {
      aliases: [
        {
          package: 'rxjs',
          imported: 'of',
          local: 'observableOf',
        },
      ],
    },
  ],
};

export const rule = ESLintUtils.RuleCreator.withoutDocs({
  ...info,
  create(context: TSESLint.RuleContext<Message, unknown[]>, options: any) {
    return (options[0] as AliasImportOptions).aliases.reduce((selectors: any, option: AliasImportOption) => {
      selectors[`ImportDeclaration[source.value = "${option.package}"] > ImportSpecifier[imported.name = "${option.imported}"][local.name != "${option.local}"]`] = (node: TSESTree.ImportSpecifier) => handleUnaliasedImport(context, option, node);
      return selectors;
    }, {});
  },
});

export const tests: NamedTests = {
  plugin: info.name,
  valid: [
    {
      name: 'correctly aliased imports',
      code: `
import { of as observableOf } from 'rxjs';
        `,
      options: [
        {
          aliases: [
            {
              package: 'rxjs',
              imported: 'of',
              local: 'observableOf',
            },
          ],
        },
      ],
    },
    {
      name: 'enforce unaliased import',
      code: `
import { combineLatest } from 'rxjs';
        `,
      options: [
        {
          aliases: [
            {
              package: 'rxjs',
              imported: 'combineLatest',
              local: 'combineLatest',
            },
          ],
        },
      ],
    },
  ],
  invalid: [
    {
      name: 'imports without alias',
      code: `
import { of } from 'rxjs';
        `,
      errors: [
        {
          messageId: 'missingAlias',
        },
      ],
      output: `
import { of as observableOf } from 'rxjs';
        `,
    },
    {
      name: 'imports under the wrong alias',
      code: `
import { of as ofSomething } from 'rxjs';
        `,
      errors: [
        {
          messageId: 'wrongAlias',
        },
      ],
      output: `
import { of as observableOf } from 'rxjs';
        `,
    },
    {
      name: 'disallow aliasing import',
      code: `
import { combineLatest as observableCombineLatest } from 'rxjs';
        `,
      errors: [
        {
          messageId: 'unnecessaryAlias',
        },
      ],
      output: `
import { combineLatest } from 'rxjs';
        `,
      options: [
        {
          aliases: [
            {
              package: 'rxjs',
              imported: 'combineLatest',
              local: 'combineLatest',
            },
          ],
        },
      ],
    },
  ],
};

/**
 * Replaces the incorrectly aliased imports with the ones defined in the defaultOptions
 *
 * @param context The current {@link TSESLint.RuleContext}
 * @param option The current {@link AliasImportOption} that needs to be handled
 * @param node The incorrect import node that should be fixed
 */
function handleUnaliasedImport(context: TSESLint.RuleContext<Message, unknown[]>, option: AliasImportOption, node: TSESTree.ImportSpecifier): void {
  const hasCorrectAliasedImport: boolean = (node.parent as TSESTree.ImportDeclaration).specifiers.find((specifier: TSESTree.ImportClause) => specifier.local.name === option.local && specifier.type === AST_NODE_TYPES.ImportSpecifier && (specifier as TSESTree.ImportSpecifier).imported.name === option.imported) !== undefined;
  if (option.imported === option.local) {
    if (hasCorrectAliasedImport) {
      context.report({
        messageId: Message.MULTIPLE_ALIASES,
        data: { local: option.local },
        node: node,
        fix(fixer: TSESLint.RuleFixer) {
          const fixes: TSESLint.RuleFix[] = [];

          const commaAfter = context.sourceCode.getTokenAfter(node, {
            filter: (token: TSESTree.Token) => token.value === ',',
          });
          if (commaAfter) {
            fixes.push(fixer.removeRange([node.range[0], commaAfter.range[1]]));
          } else {
            fixes.push(fixer.remove(node));
          }
          fixes.push(...retrieveUsageReplacementFixes(context, fixer, node, option.local));

          return fixes;
        },
      });
    } else {
      context.report({
        messageId: Message.UNNECESSARY_ALIAS,
        data: { local: option.local },
        node: node,
        fix(fixer: TSESLint.RuleFixer) {
          const fixes: TSESLint.RuleFix[] = [];

          fixes.push(fixer.replaceText(node, option.imported));
          fixes.push(...retrieveUsageReplacementFixes(context, fixer, node, option.local));

          return fixes;
        },
      });
    }
  } else {
    if (hasCorrectAliasedImport) {
      context.report({
        messageId: Message.MULTIPLE_ALIASES,
        data: { local: option.local },
        node: node,
        fix(fixer: TSESLint.RuleFixer) {
          const fixes: TSESLint.RuleFix[] = [];

          const commaAfter = context.sourceCode.getTokenAfter(node, {
            filter: (token: TSESTree.Token) => token.value === ',',
          });
          if (commaAfter) {
            fixes.push(fixer.removeRange([node.range[0], commaAfter.range[1]]));
          } else {
            fixes.push(fixer.remove(node));
          }
          fixes.push(...retrieveUsageReplacementFixes(context, fixer, node, option.local));

          return fixes;
        },
      });
    } else if (node.local.name === node.imported.name) {
      context.report({
        messageId: Message.MISSING_ALIAS,
        node: node,
        fix(fixer: TSESLint.RuleFixer) {
          const fixes: TSESLint.RuleFix[] = [];

          fixes.push(fixer.replaceText(node.local, `${option.imported} as ${option.local}`));
          fixes.push(...retrieveUsageReplacementFixes(context, fixer, node, option.local));

          return fixes;
        },
      });
    } else {
      context.report({
        messageId: Message.WRONG_ALIAS,
        data: { local: option.local },
        node: node,
        fix(fixer: TSESLint.RuleFixer) {
          const fixes: TSESLint.RuleFix[] = [];

          fixes.push(fixer.replaceText(node.local, option.local));
          fixes.push(...retrieveUsageReplacementFixes(context, fixer, node, option.local));

          return fixes;
        },
      });
    }
  }
}

/**
 * Generates the {@link TSESLint.RuleFix}s for all the usages of the incorrect import.
 *
 * @param context The current {@link TSESLint.RuleContext}
 * @param fixer The instance {@link TSESLint.RuleFixer}
 * @param node The node which needs to be replaced
 * @param newAlias The new import name
 */
function retrieveUsageReplacementFixes(context: TSESLint.RuleContext<Message, unknown[]>, fixer: TSESLint.RuleFixer, node: TSESTree.ImportSpecifier, newAlias: string): TSESLint.RuleFix[] {
  return context.sourceCode.getDeclaredVariables(node)[0].references.map((reference: Scope.Reference) => fixer.replaceText(reference.identifier, newAlias));
}