/**
 * @fileoverview A rule to ensure blank lines within blocks.
 * @author Mathias Schreck <https://github.com/lo1tuma>
 * @deprecated in ESLint v8.53.0
 */

'use strict';

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

const astUtils = require('./utils/ast-utils');

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

/** @type {import('../types').Rule.RuleModule} */
module.exports = {
  meta: {
    deprecated: {
      message: 'Formatting rules are being moved out of ESLint core.',
      url: 'https://eslint.org/blog/2023/10/deprecating-formatting-rules/',
      deprecatedSince: '8.53.0',
      availableUntil: '10.0.0',
      replacedBy: [
        {
          message:
            'ESLint Stylistic now maintains deprecated stylistic core rules.',
          url: 'https://eslint.style/guide/migration',
          plugin: {
            name: '@stylistic/eslint-plugin-js',
            url: 'https://eslint.style/packages/js',
          },
          rule: {
            name: 'padded-blocks',
            url: 'https://eslint.style/rules/js/padded-blocks',
          },
        },
      ],
    },
    type: 'layout',

    docs: {
      description: 'Require or disallow padding within blocks',
      recommended: false,
      url: 'https://eslint.org/docs/latest/rules/padded-blocks',
    },

    fixable: 'whitespace',

    schema: [
      {
        oneOf: [
          {
            enum: ['always', 'never'],
          },
          {
            type: 'object',
            properties: {
              blocks: {
                enum: ['always', 'never'],
              },
              switches: {
                enum: ['always', 'never'],
              },
              classes: {
                enum: ['always', 'never'],
              },
            },
            additionalProperties: false,
            minProperties: 1,
          },
        ],
      },
      {
        type: 'object',
        properties: {
          allowSingleLineBlocks: {
            type: 'boolean',
          },
        },
        additionalProperties: false,
      },
    ],

    messages: {
      alwaysPadBlock: 'Block must be padded by blank lines.',
      neverPadBlock: 'Block must not be padded by blank lines.',
    },
  },

  create(context) {
    const options = {};
    const typeOptions = context.options[0] || 'always';
    const exceptOptions = context.options[1] || {};

    if (typeof typeOptions === 'string') {
      const shouldHavePadding = typeOptions === 'always';

      options.blocks = shouldHavePadding;
      options.switches = shouldHavePadding;
      options.classes = shouldHavePadding;
    } else {
      if (Object.hasOwn(typeOptions, 'blocks')) {
        options.blocks = typeOptions.blocks === 'always';
      }
      if (Object.hasOwn(typeOptions, 'switches')) {
        options.switches = typeOptions.switches === 'always';
      }
      if (Object.hasOwn(typeOptions, 'classes')) {
        options.classes = typeOptions.classes === 'always';
      }
    }

    if (Object.hasOwn(exceptOptions, 'allowSingleLineBlocks')) {
      options.allowSingleLineBlocks =
        exceptOptions.allowSingleLineBlocks === true;
    }

    const sourceCode = context.sourceCode;

    /**
     * Gets the open brace token from a given node.
     * @param {ASTNode} node A BlockStatement or SwitchStatement node from which to get the open brace.
     * @returns {Token} The token of the open brace.
     */
    function getOpenBrace(node) {
      if (node.type === 'SwitchStatement') {
        return sourceCode.getTokenBefore(node.cases[0]);
      }

      if (node.type === 'StaticBlock') {
        return sourceCode.getFirstToken(node, { skip: 1 }); // skip the `static` token
      }

      // `BlockStatement` or `ClassBody`
      return sourceCode.getFirstToken(node);
    }

    /**
     * Checks if the given parameter is a comment node
     * @param {ASTNode|Token} node An AST node or token
     * @returns {boolean} True if node is a comment
     */
    function isComment(node) {
      return node.type === 'Line' || node.type === 'Block';
    }

    /**
     * Checks if there is padding between two tokens
     * @param {Token} first The first token
     * @param {Token} second The second token
     * @returns {boolean} True if there is at least a line between the tokens
     */
    function isPaddingBetweenTokens(first, second) {
      return second.loc.start.line - first.loc.end.line >= 2;
    }

    /**
     * Checks if the given token has a blank line after it.
     * @param {Token} token The token to check.
     * @returns {boolean} Whether or not the token is followed by a blank line.
     */
    function getFirstBlockToken(token) {
      let prev,
        first = token;

      do {
        prev = first;
        first = sourceCode.getTokenAfter(first, {
          includeComments: true,
        });
      } while (isComment(first) && first.loc.start.line === prev.loc.end.line);

      return first;
    }

    /**
     * Checks if the given token is preceded by a blank line.
     * @param {Token} token The token to check
     * @returns {boolean} Whether or not the token is preceded by a blank line
     */
    function getLastBlockToken(token) {
      let last = token,
        next;

      do {
        next = last;
        last = sourceCode.getTokenBefore(last, {
          includeComments: true,
        });
      } while (isComment(last) && last.loc.end.line === next.loc.start.line);

      return last;
    }

    /**
     * Checks if a node should be padded, according to the rule config.
     * @param {ASTNode} node The AST node to check.
     * @throws {Error} (Unreachable)
     * @returns {boolean} True if the node should be padded, false otherwise.
     */
    function requirePaddingFor(node) {
      switch (node.type) {
        case 'BlockStatement':
        case 'StaticBlock':
          return options.blocks;
        case 'SwitchStatement':
          return options.switches;
        case 'ClassBody':
          return options.classes;

        /* c8 ignore next */
        default:
          throw new Error('unreachable');
      }
    }

    /**
     * Checks the given BlockStatement node to be padded if the block is not empty.
     * @param {ASTNode} node The AST node of a BlockStatement.
     * @returns {void} undefined.
     */
    function checkPadding(node) {
      const openBrace = getOpenBrace(node),
        firstBlockToken = getFirstBlockToken(openBrace),
        tokenBeforeFirst = sourceCode.getTokenBefore(firstBlockToken, {
          includeComments: true,
        }),
        closeBrace = sourceCode.getLastToken(node),
        lastBlockToken = getLastBlockToken(closeBrace),
        tokenAfterLast = sourceCode.getTokenAfter(lastBlockToken, {
          includeComments: true,
        }),
        blockHasTopPadding = isPaddingBetweenTokens(
          tokenBeforeFirst,
          firstBlockToken
        ),
        blockHasBottomPadding = isPaddingBetweenTokens(
          lastBlockToken,
          tokenAfterLast
        );

      if (
        options.allowSingleLineBlocks &&
        astUtils.isTokenOnSameLine(tokenBeforeFirst, tokenAfterLast)
      ) {
        return;
      }

      if (requirePaddingFor(node)) {
        if (!blockHasTopPadding) {
          context.report({
            node,
            loc: {
              start: tokenBeforeFirst.loc.start,
              end: firstBlockToken.loc.start,
            },
            fix(fixer) {
              return fixer.insertTextAfter(tokenBeforeFirst, '\n');
            },
            messageId: 'alwaysPadBlock',
          });
        }
        if (!blockHasBottomPadding) {
          context.report({
            node,
            loc: {
              end: tokenAfterLast.loc.start,
              start: lastBlockToken.loc.end,
            },
            fix(fixer) {
              return fixer.insertTextBefore(tokenAfterLast, '\n');
            },
            messageId: 'alwaysPadBlock',
          });
        }
      } else {
        if (blockHasTopPadding) {
          context.report({
            node,
            loc: {
              start: tokenBeforeFirst.loc.start,
              end: firstBlockToken.loc.start,
            },
            fix(fixer) {
              return fixer.replaceTextRange(
                [
                  tokenBeforeFirst.range[1],
                  firstBlockToken.range[0] - firstBlockToken.loc.start.column,
                ],
                '\n'
              );
            },
            messageId: 'neverPadBlock',
          });
        }

        if (blockHasBottomPadding) {
          context.report({
            node,
            loc: {
              end: tokenAfterLast.loc.start,
              start: lastBlockToken.loc.end,
            },
            messageId: 'neverPadBlock',
            fix(fixer) {
              return fixer.replaceTextRange(
                [
                  lastBlockToken.range[1],
                  tokenAfterLast.range[0] - tokenAfterLast.loc.start.column,
                ],
                '\n'
              );
            },
          });
        }
      }
    }

    const rule = {};

    if (Object.hasOwn(options, 'switches')) {
      rule.SwitchStatement = function (node) {
        if (node.cases.length === 0) {
          return;
        }
        checkPadding(node);
      };
    }

    if (Object.hasOwn(options, 'blocks')) {
      rule.BlockStatement = function (node) {
        if (node.body.length === 0) {
          return;
        }
        checkPadding(node);
      };
      rule.StaticBlock = rule.BlockStatement;
    }

    if (Object.hasOwn(options, 'classes')) {
      rule.ClassBody = function (node) {
        if (node.body.length === 0) {
          return;
        }
        checkPadding(node);
      };
    }

    return rule;
  },
};