import _ from 'lodash';

import {
  isFlowFileAnnotation,
  fuzzyStringMatch,
} from '../utilities';

const defaults = {
  annotationStyle: 'none',
  strict: false,
};

const looksLikeFlowFileAnnotation = (comment) => /@(?:no)?flo/ui.test(comment);

const isValidAnnotationStyle = (node, style) => {
  if (style === 'none') {
    return true;
  }

  return style === node.type.toLowerCase();
};

const checkAnnotationSpelling = (comment) => /@[a-z]+\b/u.test(comment) && fuzzyStringMatch(comment.replace(/no/ui, ''), '@flow', 0.2);

const isFlowStrict = (comment) => /^@flow\sstrict\b/u.test(comment);

const noFlowAnnotation = (comment) => /^@noflow\b/u.test(comment);

const schema = [
  {
    enum: ['always', 'never'],
    type: 'string',
  },
  {
    additionalProperties: false,
    properties: {
      annotationStyle: {
        enum: ['none', 'line', 'block'],
        type: 'string',
      },
      strict: {
        enum: [true, false],
        type: 'boolean',
      },
    },
    type: 'object',
  },
];

const create = (context) => {
  const always = context.options[0] === 'always';
  const style = _.get(context, 'options[1].annotationStyle', defaults.annotationStyle);
  const flowStrict = _.get(context, 'options[1].strict', defaults.strict);

  return {
    Program(node) {
      const firstToken = node.tokens[0];

      const potentialFlowFileAnnotation = _.find(
        context.getSourceCode().getAllComments(),
        (comment) => looksLikeFlowFileAnnotation(comment.value),
      );

      if (potentialFlowFileAnnotation) {
        if (firstToken && firstToken.range[0] < potentialFlowFileAnnotation.range[0]) {
          context.report({ message: 'Flow file annotation not at the top of the file.', node: potentialFlowFileAnnotation });
        }

        const annotationValue = potentialFlowFileAnnotation.value.trim();

        if (isFlowFileAnnotation(annotationValue)) {
          if (!isValidAnnotationStyle(potentialFlowFileAnnotation, style)) {
            const annotation = style === 'line' ? `// ${annotationValue}` : `/* ${annotationValue} */`;

            context.report({
              fix: (fixer) => fixer.replaceTextRange(
                [
                  potentialFlowFileAnnotation.range[0],
                  potentialFlowFileAnnotation.range[1],
                ],
                annotation,
              ),
              message: `Flow file annotation style must be \`${annotation}\``,
              node: potentialFlowFileAnnotation,
            });
          }

          if (!noFlowAnnotation(annotationValue) && flowStrict && !isFlowStrict(annotationValue)) {
            const str = style === 'line' ? '`// @flow strict`' : '`/* @flow strict */`';

            context.report({
              fix: (fixer) => {
                const annotation = ['line', 'none'].includes(style) ? '// @flow strict' : '/* @flow strict */';

                return fixer.replaceTextRange([
                  potentialFlowFileAnnotation.range[0],
                  potentialFlowFileAnnotation.range[1],
                ], annotation);
              },
              message: `Strict Flow file annotation is required, must be ${str}`,
              node,
            });
          }
        } else if (checkAnnotationSpelling(annotationValue)) {
          context.report({ message: 'Misspelled or malformed Flow file annotation.', node: potentialFlowFileAnnotation });
        } else {
          context.report({ message: 'Malformed Flow file annotation.', node: potentialFlowFileAnnotation });
        }
      } else if (always && !_.get(context, 'settings[\'ft-flow\'].onlyFilesWithFlowAnnotation')) {
        context.report({
          fix: (fixer) => {
            let annotation;

            if (flowStrict) {
              annotation = ['line', 'none'].includes(style) ? '// @flow strict\n' : '/* @flow strict */\n';
            } else {
              annotation = ['line', 'none'].includes(style) ? '// @flow\n' : '/* @flow */\n';
            }

            const firstComment = node.comments[0];

            if (firstComment && firstComment.type === 'Shebang') {
              return fixer
                .replaceTextRange(
                  [
                    firstComment.range[1],
                    firstComment.range[1],
                  ],
                  `\n${annotation.trim()}`,
                );
            }

            return fixer
              .replaceTextRange(
                [
                  node.range[0],
                  node.range[0],
                ],
                annotation,
              );
          },
          message: 'Flow file annotation is missing.',
          node,
        });
      }
    },
  };
};

export default {
  create,
  meta: {
    fixable: 'code',
  },
  schema,
};