const nql = require('@tryghost/nql');
const {BadRequestError} = require('@tryghost/errors');
const tpl = require('@tryghost/tpl');
const errors = require('@tryghost/errors');
const ObjectId = require('bson-objectid').default;

const messages = {
    invalidVisibilityFilter: 'Invalid visibility filter.',
    invalidVisibility: 'Invalid visibility value.',
    invalidTiers: 'Invalid tiers value.',
    invalidEmailSegment: 'The email segment parameter doesn\'t contain a valid filter',
    unsupportedBulkAction: 'Unsupported bulk action'
};

class PostsService {
    constructor({urlUtils, models, isSet, stats, emailService, postsExporter}) {
        this.urlUtils = urlUtils;
        this.models = models;
        this.isSet = isSet;
        this.stats = stats;
        this.emailService = emailService;
        this.postsExporter = postsExporter;
    }

    async editPost(frame) {
        // Make sure the newsletter is matching an active newsletter
        // Note that this option is simply ignored if the post isn't published or scheduled
        if (frame.options.newsletter && frame.options.email_segment) {
            if (frame.options.email_segment !== 'all') {
                // check filter is valid
                try {
                    await this.models.Member.findPage({filter: frame.options.email_segment, limit: 1});
                } catch (err) {
                    return Promise.reject(new BadRequestError({
                        message: tpl(messages.invalidEmailSegment),
                        context: err.message
                    }));
                }
            }
        }

        const model = await this.models.Post.edit(frame.data.posts[0], frame.options);

        /**Handle newsletter email */
        if (model.get('newsletter_id')) {
            const sendEmail = model.wasChanged() && this.shouldSendEmail(model.get('status'), model.previous('status'));

            if (sendEmail) {
                let postEmail = model.relations.email;
                let email;

                if (!postEmail) {
                    email = await this.emailService.createEmail(model);
                } else if (postEmail && postEmail.get('status') === 'failed') {
                    email = await this.emailService.retryEmail(postEmail);
                }
                if (email) {
                    model.set('email', email);
                }
            }
        }

        return model;
    }

    #mergeFilters(...filters) {
        return filters.filter(filter => filter).map(f => `(${f})`).join('+');
    }

    async bulkEdit(data, options) {
        if (data.action === 'unpublish') {
            return await this.#updatePosts({status: 'draft'}, {filter: this.#mergeFilters('status:published', options.filter)});
        }
        if (data.action === 'feature') {
            return await this.#updatePosts({featured: true}, {filter: options.filter});
        }
        if (data.action === 'unfeature') {
            return await this.#updatePosts({featured: false}, {filter: options.filter});
        }
        if (data.action === 'access') {
            if (!['public', 'members', 'paid', 'tiers'].includes(data.meta.visibility)) {
                throw new errors.IncorrectUsageError({
                    message: tpl(messages.invalidVisibility)
                });
            }
            let tiers = undefined;
            if (data.meta.visibility === 'tiers') {
                if (!Array.isArray(data.meta.tiers)) {
                    throw new errors.IncorrectUsageError({
                        message: tpl(messages.invalidTiers)
                    });
                }
                tiers = data.meta.tiers;
            }
            return await this.#updatePosts({visibility: data.meta.visibility, tiers}, {filter: options.filter});
        }
        if (data.action === 'addTag') {
            return await this.#bulkAddTags({tags: data.meta.tags}, {filter: options.filter});
        }
        throw new errors.IncorrectUsageError({
            message: tpl(messages.unsupportedBulkAction)
        });
    }

    /**
     * @param {object} data
     * @param {string[]} data.tags - Array of tag ids to add to the post
     * @param {object} options
     * @param {string} options.filter - An NQL Filter
     */
    async #bulkAddTags(data, options) {
        if (!options.transacting) {
            return await this.models.Post.transaction(async (transacting) => {
                return await this.#bulkAddTags(data, {
                    ...options,
                    transacting
                });
            });
        }

        const postRows = await this.models.Post.getFilteredCollectionQuery({
            filter: options.filter,
            status: 'all'
        }).select('posts.id');

        const postTags = data.tags.reduce((pt, tagId) => {
            return pt.concat(postRows.map((post) => {
                return {
                    id: (new ObjectId()).toHexString(),
                    post_id: post.id,
                    tag_id: tagId,
                    sort_order: 0
                };
            }));
        }, []);

        await options.transacting('posts_tags').insert(postTags);

        return true;
    }

    /**
     * @param {object} data
     * @param {string[]} data.tags - Array of tag ids to add to the post
     * @param {object} options
     * @param {string} options.filter - An NQL Filter
     */
    async #bulkRemoveTags(data, options) {
        if (!options.transacting) {
            return await this.models.Post.transaction(async (transacting) => {
                return await this.#bulkRemoveTags(data, {
                    ...options,
                    transacting
                });
            });
        }

        const postRows = await this.models.Post.getFilteredCollectionQuery({
            filter: options.filter,
            status: 'all'
        }).select('posts.id');

        await options.transacting('posts_tags').whereIn('post_id', postRows.map(post => post.id)).whereIn('tag_id', data.tags).del();

        return true;
    }

    async bulkDestroy(options) {
        if (!options.transacting) {
            return await this.models.Post.transaction(async (transacting) => {
                return await this.bulkDestroy({
                    ...options,
                    transacting
                });
            });
        }

        const postRows = await this.models.Post.getFilteredCollectionQuery({
            filter: options.filter,
            status: 'all',
            transacting: options.transacting
        }).leftJoin('emails', 'posts.id', 'emails.post_id').select('posts.id', 'emails.id as email_id');
        const deleteIds = postRows.map(row => row.id);

        // We also need to collect the email ids because the email relation doesn't have cascase, and we need to delete the related relations of the post
        const deleteEmailIds = postRows.map(row => row.email_id).filter(id => !!id);

        const postTablesToDelete = [
            'posts_authors',
            'posts_tags',
            'posts_meta',
            'mobiledoc_revisions',
            'post_revisions',
            'posts_products'
        ];
        const emailTablesToDelete = [
            'email_recipient_failures',
            'email_recipients',
            'email_batches',
            'email_spam_complaint_events'
        ];

        // Don't clear, but set relation to null
        const emailTablesToSetNull = [
            'suppressions'
        ];

        for (const table of postTablesToDelete) {
            await this.models.Post.bulkDestroy(deleteIds, table, {
                column: 'post_id',
                transacting: options.transacting,
                throwErrors: true
            });
        }

        for (const table of emailTablesToDelete) {
            await this.models.Post.bulkDestroy(deleteEmailIds, table, {
                column: 'email_id',
                transacting: options.transacting,
                throwErrors: true
            });
        }

        for (const table of emailTablesToSetNull) {
            await this.models.Post.bulkEdit(deleteEmailIds, table, {
                data: {email_id: null},
                column: 'email_id',
                transacting: options.transacting,
                throwErrors: true
            });
        }

        // Posts and emails
        await this.models.Post.bulkDestroy(deleteEmailIds, 'emails', {transacting: options.transacting, throwErrors: true});
        return await this.models.Post.bulkDestroy(deleteIds, 'posts', {transacting: options.transacting, throwErrors: true});
    }

    async export(frame) {
        return await this.postsExporter.export(frame.options);
    }

    async #updatePosts(data, options) {
        if (!options.transacting) {
            return await this.models.Post.transaction(async (transacting) => {
                return await this.#updatePosts(data, {
                    ...options,
                    transacting
                });
            });
        }

        const postRows = await this.models.Post.getFilteredCollectionQuery({
            filter: options.filter,
            status: 'all',
            transacting: options.transacting
        }).select('posts.id');

        const editIds = postRows.map(row => row.id);

        let tiers = undefined;
        if (data.tiers) {
            tiers = data.tiers;
            delete data.tiers;
        }

        const result = await this.models.Post.bulkEdit(editIds, 'posts', {
            data,
            transacting: options.transacting,
            throwErrors: true
        });

        // Update tiers
        if (tiers) {
            // First delete all
            await this.models.Post.bulkDestroy(editIds, 'posts_products', {
                column: 'post_id',
                transacting: options.transacting,
                throwErrors: true
            });

            // Then add again
            const toInsert = [];
            for (const postId of editIds) {
                for (const [index, tier] of tiers.entries()) {
                    if (typeof tier.id === 'string') {
                        toInsert.push({
                            id: ObjectId().toHexString(),
                            post_id: postId,
                            product_id: tier.id,
                            sort_order: index
                        });
                    }
                }
            }
            await this.models.Post.bulkAdd(toInsert, 'posts_products', {
                transacting: options.transacting,
                throwErrors: true
            });
        }

        return result;
    }

    async getProductsFromVisibilityFilter(visibilityFilter) {
        try {
            const allProducts = await this.models.Product.findAll();
            const visibilityFilterJson = nql(visibilityFilter).toJSON();
            const productsData = (visibilityFilterJson.product ? [visibilityFilterJson] : visibilityFilterJson.$or) || [];
            const tiers = productsData
                .map((data) => {
                    return allProducts.find((p) => {
                        return p.get('slug') === data.product;
                    });
                }).filter(p => !!p).map((d) => {
                    return d.toJSON();
                });
            return tiers;
        } catch (err) {
            return Promise.reject(new BadRequestError({
                message: tpl(messages.invalidVisibilityFilter),
                context: err.message
            }));
        }
    }

    /**
     * Calculates if the email should be tried to be sent out
     * @private
     * @param {String} currentStatus current status from the post model
     * @param {String} previousStatus previous status from the post model
     * @returns {Boolean}
     */
    shouldSendEmail(currentStatus, previousStatus) {
        return (['published', 'sent'].includes(currentStatus))
            && (!['published', 'sent'].includes(previousStatus));
    }

    handleCacheInvalidation(model) {
        let cacheInvalidate;

        if (
            model.get('status') === 'published' && model.wasChanged() ||
            model.get('status') === 'draft' && model.previous('status') === 'published'
        ) {
            cacheInvalidate = true;
        } else if (
            model.get('status') === 'draft' && model.previous('status') !== 'published' ||
            model.get('status') === 'scheduled' && model.wasChanged()
        ) {
            cacheInvalidate = {
                value: this.urlUtils.urlFor({
                    relativeUrl: this.urlUtils.urlJoin('/p', model.get('uuid'), '/')
                })
            };
        } else {
            cacheInvalidate = false;
        }

        return cacheInvalidate;
    }
}

module.exports = PostsService;