import AJV from 'ajv';
import ajvErrors from 'ajv-errors';
import { formatExtensions, frontmatterFormats, extensionFormatters } from 'Formats/formats';
import { IDENTIFIER_FIELDS } from 'Constants/fieldInference';

/**
 * Config for fields in both file and folder collections.
 */
const fieldsConfig = {
  type: 'array',
  minItems: 1,
  items: {
    // ------- Each field: -------
    type: 'object',
    properties: {
      name: { type: 'string' },
      label: { type: 'string' },
      widget: { type: 'string' },
      required: { type: 'boolean' },
    },
    required: ['name'],
  },
};

/**
 * The schema had to be wrapped in a function to
 * fix a circular dependency problem for WebPack,
 * where the imports get resolved asyncronously.
 */
const getConfigSchema = () => ({
  type: 'object',
  properties: {
    backend: {
      type: 'object',
      properties: { name: { type: 'string', examples: ['test-repo'] } },
      required: ['name'],
    },
    display_url: { type: 'string', examples: ['https://example.com'] },
    media_folder: { type: 'string', examples: ['assets/uploads'] },
    public_folder: { type: 'string', examples: ['/uploads'] },
    publish_mode: {
      type: 'string',
      enum: ['editorial_workflow'],
      examples: ['editorial_workflow'],
    },
    slug: {
      type: 'object',
      properties: {
        encoding: { type: 'string', enum: ['unicode', 'ascii'] },
        clean_accents: { type: 'boolean' },
      },
    },
    collections: {
      type: 'array',
      minItems: 1,
      items: {
        // ------- Each collection: -------
        type: 'object',
        properties: {
          name: { type: 'string' },
          label: { type: 'string' },
          label_singular: { type: 'string' },
          description: { type: 'string' },
          folder: { type: 'string' },
          files: {
            type: 'array',
            items: {
              // ------- Each file: -------
              type: 'object',
              properties: {
                name: { type: 'string' },
                label: { type: 'string' },
                label_singular: { type: 'string' },
                description: { type: 'string' },
                file: { type: 'string' },
                fields: fieldsConfig,
              },
              required: ['name', 'label', 'file', 'fields'],
            },
          },
          slug: { type: 'string' },
          create: { type: 'boolean' },
          editor: {
            type: 'object',
            properties: {
              preview: { type: 'boolean' },
            },
          },
          format: { type: 'string', enum: Object.keys(formatExtensions) },
          extension: { type: 'string' },
          frontmatter_delimiter: { type: 'string' },
          fields: fieldsConfig,
        },
        required: ['name', 'label'],
        oneOf: [{ required: ['files'] }, { required: ['folder', 'fields'] }],
        if: { required: ['extension'] },
        then: {
          // Cannot infer format from extension.
          if: {
            properties: {
              extension: { enum: Object.keys(extensionFormatters) },
            },
          },
          else: { required: ['format'] },
        },
        dependencies: {
          frontmatter_delimiter: {
            properties: {
              format: { enum: frontmatterFormats },
            },
            required: ['format'],
          },
          folder: {
            errorMessage: {
              _: 'must have a field that is a valid entry identifier',
            },
            properties: {
              fields: {
                contains: {
                  properties: {
                    name: { enum: IDENTIFIER_FIELDS },
                  },
                },
              },
            },
          },
        },
      },
    },
  },
  required: ['backend', 'media_folder', 'collections'],
});

class ConfigError extends Error {
  constructor(errors, ...args) {
    const message = errors
      .map(({ message, dataPath }) => {
        const dotPath = dataPath
          .slice(1)
          .split('/')
          .map(seg => (seg.match(/^\d+$/) ? `[${seg}]` : `.${seg}`))
          .join('')
          .slice(1);
        return `${dotPath ? `'${dotPath}'` : 'config'} ${message}`;
      })
      .join('\n');
    super(message, ...args);

    this.errors = errors;
    this.message = message;
  }

  toString() {
    return this.message;
  }
}

/**
 * `validateConfig` is a pure function. It does not mutate
 * the config that is passed in.
 */
export function validateConfig(config) {
  const ajv = new AJV({ allErrors: true, jsonPointers: true });
  ajvErrors(ajv);

  const valid = ajv.validate(getConfigSchema(), config);
  if (!valid) {
    console.error('Config Errors', ajv.errors);
    throw new ConfigError(ajv.errors);
  }
}