const errors = require('@tryghost/errors');
const nql = require('@tryghost/nql');
const mingo = require('mingo');
const {replaceFilters, expandFilters, splitFilter, getUsedKeys, chainTransformers, mapKeys} = require('@tryghost/mongo-utils');

/**
 * This mongo transformer ignores the provided filter option and replaces the filter with a custom filter that was provided to the transformer. Allowing us to set a mongo filter instead of a string based NQL filter.
 */
function replaceCustomFilterTransformer(filter) {
    // Instead of adding an existing filter, we replace a filter, because mongo transformers are only applied if there is any filter (so not executed for empty filters)
    return function (existingFilter) {
        return replaceFilters(existingFilter, {
            custom: filter
        });
    };
}

module.exports = class EventRepository {
    constructor({
        EmailRecipient,
        MemberSubscribeEvent,
        MemberPaymentEvent,
        MemberStatusEvent,
        MemberLoginEvent,
        MemberCreatedEvent,
        SubscriptionCreatedEvent,
        MemberPaidSubscriptionEvent,
        MemberLinkClickEvent,
        MemberFeedback,
        Comment,
        labsService,
        memberAttributionService
    }) {
        this._MemberSubscribeEvent = MemberSubscribeEvent;
        this._MemberPaidSubscriptionEvent = MemberPaidSubscriptionEvent;
        this._MemberPaymentEvent = MemberPaymentEvent;
        this._MemberStatusEvent = MemberStatusEvent;
        this._MemberLoginEvent = MemberLoginEvent;
        this._EmailRecipient = EmailRecipient;
        this._Comment = Comment;
        this._labsService = labsService;
        this._MemberCreatedEvent = MemberCreatedEvent;
        this._SubscriptionCreatedEvent = SubscriptionCreatedEvent;
        this._MemberLinkClickEvent = MemberLinkClickEvent;
        this._MemberFeedback = MemberFeedback;
        this._memberAttributionService = memberAttributionService;
    }

    async getEventTimeline(options = {}) {
        if (!options.limit) {
            options.limit = 10;
        }
        
        const [typeFilter, otherFilter] = this.getNQLSubset(options.filter);

        // Changing this order might need a change in the query functions
        // because of the different underlying models.
        options.order = 'created_at desc, id desc';

        // Create a list of all events that can be queried
        const pageActions = [
            {type: 'comment_event', action: 'getCommentEvents'},
            {type: 'click_event', action: 'getClickEvents'},
            {type: 'signup_event', action: 'getSignupEvents'},
            {type: 'subscription_event', action: 'getSubscriptionEvents'}
        ];

        // Some events are not filterable by post_id
        if (!getUsedKeys(otherFilter).includes('data.post_id')) {
            pageActions.push(
                {type: 'newsletter_event', action: 'getNewsletterSubscriptionEvents'},
                {type: 'login_event', action: 'getLoginEvents'},
                {type: 'payment_event', action: 'getPaymentEvents'}
            );
        }

        if (this._EmailRecipient) {
            pageActions.push({type: 'email_sent_event', action: 'getEmailSentEvents'});
            pageActions.push({type: 'email_delivered_event', action: 'getEmailDeliveredEvents'});
            pageActions.push({type: 'email_opened_event', action: 'getEmailOpenedEvents'});
            pageActions.push({type: 'email_failed_event', action: 'getEmailFailedEvents'});
        }

        if (this._labsService.isSet('audienceFeedback')) {
            pageActions.push({type: 'feedback_event', action: 'getFeedbackEvents'});
        }

        //Filter events to query
        let filteredPages = pageActions;
        if (typeFilter) {
            // Ideally we should be able to create a NQL filter without having a string
            const query = new mingo.Query(typeFilter);
            filteredPages = filteredPages.filter(page => query.test(page));
        }

        //Start the promises
        const pages = filteredPages.map((page) => {
            return this[page.action](options, otherFilter);
        });

        const allEventPages = await Promise.all(pages);

        const allEvents = allEventPages.flatMap(page => page.data);
        const totalEvents = allEventPages.reduce((accumulator, page) => accumulator + page.meta.pagination.total, 0);

        return {
            events: allEvents.sort(
                (a, b) => {
                    const diff = new Date(b.data.created_at).getTime() - new Date(a.data.created_at).getTime();
                    if (diff !== 0) {
                        return diff;
                    }
                    return b.data.id.localeCompare(a.data.id);
                }
            ).slice(0, options.limit),
            meta: {
                pagination: {
                    limit: options.limit,
                    total: totalEvents,
                    pages: options.limit > 0 ? Math.ceil(totalEvents / options.limit) : null,

                    // Other values are unavailable (not possible to calculate easily)
                    page: null,
                    next: null,
                    prev: null
                }
            }
        };
    }

    async registerPayment(data) {
        await this._MemberPaymentEvent.add({
            ...data,
            source: 'stripe'
        });
    }

    async getNewsletterSubscriptionEvents(options = {}, filter) {
        options = {
            ...options,
            withRelated: ['member', 'newsletter'],
            filter: 'custom:true',
            mongoTransformer: chainTransformers(
                // First set the filter manually
                replaceCustomFilterTransformer(filter),

                // Map the used keys in that filter
                ...mapKeys({
                    'data.created_at': 'created_at',
                    'data.source': 'source',
                    'data.member_id': 'member_id'
                })
            )
        };

        const {data: models, meta} = await this._MemberSubscribeEvent.findPage(options);

        const data = models.map((model) => {
            return {
                type: 'newsletter_event',
                data: model.toJSON(options)
            };
        });

        return {
            data,
            meta
        };
    }

    async getSubscriptionEvents(options = {}, filter) {
        if (!this._labsService.isSet('memberAttribution')){
            options = {
                ...options,
                withRelated: ['member'],
                filter: 'custom:true',
                mongoTransformer: chainTransformers(
                    // First set the filter manually
                    replaceCustomFilterTransformer(filter),
    
                    // Map the used keys in that filter
                    ...mapKeys({
                        'data.created_at': 'created_at',
                        'data.member_id': 'member_id'
                    })
                )
            };
    
            const {data: models, meta} = await this._MemberPaidSubscriptionEvent.findPage(options);
    
            const data = models.map((model) => {
                return {
                    type: 'subscription_event',
                    data: model.toJSON(options)
                };
            });
    
            return {
                data,
                meta
            };
        }

        options = {
            ...options,
            withRelated: [
                'member', 
                'subscriptionCreatedEvent.postAttribution', 
                'subscriptionCreatedEvent.userAttribution', 
                'subscriptionCreatedEvent.tagAttribution', 
                'subscriptionCreatedEvent.memberCreatedEvent',

                // This is rediculous, but we need the tier name (we'll be able to shorten this later when we switch to the subscriptions table)
                'stripeSubscription.stripePrice.stripeProduct.product'
            ],
            filter: 'custom:true',
            mongoTransformer: chainTransformers(
                // First set the filter manually
                replaceCustomFilterTransformer(filter),

                // Map the used keys in that filter
                ...mapKeys({
                    'data.created_at': 'created_at',
                    'data.member_id': 'member_id'
                }),

                (f) => {
                    // Special one: when data.post_id is used, replace it with two filters: subscriptionCreatedEvent.attribution_id:x+subscriptionCreatedEvent.attribution_type:post
                    return expandFilters(f, [{
                        key: 'data.post_id',
                        replacement: 'subscriptionCreatedEvent.attribution_id',
                        expansion: {'subscriptionCreatedEvent.attribution_type': 'post'}
                    }]);
                }
            )
        };

        const {data: models, meta} = await this._MemberPaidSubscriptionEvent.findPage(options);

        const data = models.map((model) => {
            const d = {
                ...model.toJSON(options),
                attribution: model.get('type') === 'created' && model.related('subscriptionCreatedEvent') && model.related('subscriptionCreatedEvent').id ? this._memberAttributionService.getEventAttribution(model.related('subscriptionCreatedEvent')) : null,
                signup: model.get('type') === 'created' && model.related('subscriptionCreatedEvent') && model.related('subscriptionCreatedEvent').id && model.related('subscriptionCreatedEvent').related('memberCreatedEvent') && model.related('subscriptionCreatedEvent').related('memberCreatedEvent').id ? true : false,
                tierName: model.related('stripeSubscription') && model.related('stripeSubscription').related('stripePrice') && model.related('stripeSubscription').related('stripePrice').related('stripeProduct') && model.related('stripeSubscription').related('stripePrice').related('stripeProduct').related('product') ? model.related('stripeSubscription').related('stripePrice').related('stripeProduct').related('product').get('name') : null
            };
            delete d.stripeSubscription;
            return {
                type: 'subscription_event',
                data: d
            };
        });

        return {
            data,
            meta
        };
    }

    async getPaymentEvents(options = {}, filter) {
        options = {
            ...options,
            withRelated: ['member'],
            filter: 'custom:true',
            mongoTransformer: chainTransformers(
                // First set the filter manually
                replaceCustomFilterTransformer(filter),

                // Map the used keys in that filter
                ...mapKeys({
                    'data.created_at': 'created_at',
                    'data.member_id': 'member_id'
                })
            )
        };

        const {data: models, meta} = await this._MemberPaymentEvent.findPage(options);

        const data = models.map((model) => {
            return {
                type: 'payment_event',
                data: model.toJSON(options)
            };
        });

        return {
            data,
            meta
        };
    }

    async getLoginEvents(options = {}, filter) {
        options = {
            ...options,
            withRelated: ['member'],
            filter: 'custom:true',
            mongoTransformer: chainTransformers(
                // First set the filter manually
                replaceCustomFilterTransformer(filter),

                // Map the used keys in that filter
                ...mapKeys({
                    'data.created_at': 'created_at',
                    'data.member_id': 'member_id'
                })
            )
        };

        const {data: models, meta} = await this._MemberLoginEvent.findPage(options);

        const data = models.map((model) => {
            return {
                type: 'login_event',
                data: model.toJSON(options)
            };
        });

        return {
            data,
            meta
        };
    }

    async getSignupEvents(options = {}, filter) {
        if (!this._labsService.isSet('memberAttribution')){
            options = {
                ...options,
                withRelated: ['member'],
                filter: 'from_status:null+custom:true',
                mongoTransformer: chainTransformers(
                    // First set the filter manually
                    replaceCustomFilterTransformer(filter),
    
                    // Map the used keys in that filter
                    ...mapKeys({
                        'data.created_at': 'created_at',
                        'data.member_id': 'member_id'
                    })
                )
            };
    
            const {data: models, meta} = await this._MemberStatusEvent.findPage(options);
    
            const data = models.map((model) => {
                return {
                    type: 'signup_event',
                    data: model.toJSON(options)
                };
            });
    
            return {
                data,
                meta
            };
        }

        return this.getCreatedEvents(options, filter);
    }

    async getCreatedEvents(options = {}, filter) {
        options = {
            ...options,
            withRelated: [
                'member', 
                'postAttribution', 
                'userAttribution', 
                'tagAttribution'
            ],
            filter: 'subscriptionCreatedEvent.id:null+custom:true',
            mongoTransformer: chainTransformers(
                // First set the filter manually
                replaceCustomFilterTransformer(filter),

                // Map the used keys in that filter
                ...mapKeys({
                    'data.created_at': 'created_at',
                    'data.member_id': 'member_id',
                    'data.source': 'source'
                }),

                (f) => {
                    // Special one: when data.post_id is used, replace it with two filters: attribution_id:x+attribution_type:post
                    return expandFilters(f, [{
                        key: 'data.post_id',
                        replacement: 'attribution_id',
                        expansion: {attribution_type: 'post'}
                    }]);
                }
            )
        };

        const {data: models, meta} = await this._MemberCreatedEvent.findPage(options);

        const data = models.map((model) => {
            return {
                type: 'signup_event',
                data: {
                    ...model.toJSON(options),
                    attribution: this._memberAttributionService.getEventAttribution(model)
                }
            };
        });

        return {
            data,
            meta
        };
    }

    async getCommentEvents(options = {}, filter) {
        options = {
            ...options,
            withRelated: ['member', 'post', 'parent'],
            filter: 'member_id:-null+custom:true',
            mongoTransformer: chainTransformers(
                // First set the filter manually
                replaceCustomFilterTransformer(filter),

                // Map the used keys in that filter
                ...mapKeys({
                    'data.created_at': 'created_at',
                    'data.member_id': 'member_id',
                    'data.post_id': 'post_id'
                })
            )
        };

        const {data: models, meta} = await this._Comment.findPage(options);

        const data = models.map((model) => {
            return {
                type: 'comment_event',
                data: model.toJSON(options)
            };
        });

        return {
            data,
            meta
        };
    }

    async getClickEvents(options = {}, filter) {
        options = {
            ...options,
            withRelated: ['member', 'link', 'link.post'],
            filter: 'custom:true',
            mongoTransformer: chainTransformers(
                // First set the filter manually
                replaceCustomFilterTransformer(filter),

                // Map the used keys in that filter
                ...mapKeys({
                    'data.created_at': 'created_at',
                    'data.member_id': 'member_id',
                    'data.post_id': 'post_id'
                })
            )
        };

        const {data: models, meta} = await this._MemberLinkClickEvent.findPage(options);

        const data = models.map((model) => {
            return {
                type: 'click_event',
                data: model.toJSON(options)
            };
        });

        return {
            data,
            meta
        };
    }

    async getFeedbackEvents(options = {}, filter) {
        options = {
            ...options,
            withRelated: ['member', 'post'],
            filter: 'custom:true',
            mongoTransformer: chainTransformers(
                // First set the filter manually
                replaceCustomFilterTransformer(filter),

                // Map the used keys in that filter
                ...mapKeys({
                    'data.created_at': 'created_at',
                    'data.member_id': 'member_id',
                    'data.post_id': 'post_id'
                })
            )
        };

        const {data: models, meta} = await this._MemberFeedback.findPage(options);

        const data = models.map((model) => {
            return {
                type: 'feedback_event',
                data: model.toJSON(options)
            };
        });

        return {
            data,
            meta
        };
    }

    async getEmailSentEvents(options = {}, filter) {
        options = {
            ...options,
            withRelated: ['member', 'email'],
            filter: 'failed_at:null+processed_at:-null+custom:true',
            mongoTransformer: chainTransformers(
                // First set the filter manually
                replaceCustomFilterTransformer(filter),

                // Map the used keys in that filter
                ...mapKeys({
                    'data.created_at': 'processed_at',
                    'data.member_id': 'member_id',
                    'data.post_id': 'email.post_id'
                })
            )
        };
        options.order = options.order.replace(/created_at/g, 'processed_at');

        const {data: models, meta} = await this._EmailRecipient.findPage(
            options
        );

        const data = models.map((model) => {
            return {
                type: 'email_sent_event',
                data: {
                    id: model.id,
                    member_id: model.get('member_id'),
                    created_at: model.get('processed_at'),
                    member: model.related('member').toJSON(),
                    email: model.related('email').toJSON()
                }
            };
        });

        return {
            data,
            meta
        };
    }

    async getEmailDeliveredEvents(options = {}, filter) {
        options = {
            ...options,
            withRelated: ['member', 'email'],
            filter: 'delivered_at:-null+custom:true',
            mongoTransformer: chainTransformers(
                // First set the filter manually
                replaceCustomFilterTransformer(filter),

                // Map the used keys in that filter
                ...mapKeys({
                    'data.created_at': 'delivered_at',
                    'data.member_id': 'member_id',
                    'data.post_id': 'email.post_id'
                })
            )
        };
        options.order = options.order.replace(/created_at/g, 'delivered_at');

        const {data: models, meta} = await this._EmailRecipient.findPage(
            options
        );

        const data = models.map((model) => {
            return {
                type: 'email_delivered_event',
                data: {
                    id: model.id,
                    member_id: model.get('member_id'),
                    created_at: model.get('delivered_at'),
                    member: model.related('member').toJSON(),
                    email: model.related('email').toJSON()
                }
            };
        });

        return {
            data,
            meta
        };
    }

    async getEmailOpenedEvents(options = {}, filter) {
        options = {
            ...options,
            withRelated: ['member', 'email'],
            filter: 'opened_at:-null+custom:true',
            mongoTransformer: chainTransformers(
                // First set the filter manually
                replaceCustomFilterTransformer(filter),

                // Map the used keys in that filter
                ...mapKeys({
                    'data.created_at': 'opened_at',
                    'data.member_id': 'member_id',
                    'data.post_id': 'email.post_id'
                })
            )
        };
        options.order = options.order.replace(/created_at/g, 'opened_at');

        const {data: models, meta} = await this._EmailRecipient.findPage(
            options
        );

        const data = models.map((model) => {
            return {
                type: 'email_opened_event',
                data: {
                    id: model.id,
                    member_id: model.get('member_id'),
                    created_at: model.get('opened_at'),
                    member: model.related('member').toJSON(),
                    email: model.related('email').toJSON()
                }
            };
        });

        return {
            data,
            meta
        };
    }

    async getEmailFailedEvents(options = {}, filter) {
        options = {
            ...options,
            withRelated: ['member', 'email'],
            filter: 'failed_at:-null+custom:true',
            mongoTransformer: chainTransformers(
                // First set the filter manually
                replaceCustomFilterTransformer(filter),

                // Map the used keys in that filter
                ...mapKeys({
                    'data.created_at': 'failed_at',
                    'data.member_id': 'member_id',
                    'data.post_id': 'email.post_id'
                })
            )
        };
        options.order = options.order.replace(/created_at/g, 'failed_at');

        const {data: models, meta} = await this._EmailRecipient.findPage(
            options
        );

        const data = models.map((model) => {
            return {
                type: 'email_failed_event',
                data: {
                    id: model.id,
                    member_id: model.get('member_id'),
                    created_at: model.get('failed_at'),
                    member: model.related('member').toJSON(),
                    email: model.related('email').toJSON()
                }
            };
        });

        return {
            data,
            meta
        };
    }

    /**
     * Split the filter in two parts:
     * - One with 'type' that will be applied to all the pages
     * - Other filter that will be applied to each individual page
     * 
     * Throws if splitting is not possible (e.g. OR'ing type with other filters)
     */
    getNQLSubset(filter) {
        if (!filter) {
            return [undefined, undefined];
        }

        const allowList = ['data.created_at', 'data.member_id', 'data.post_id', 'type', 'id'];
        const parsed = nql(filter).parse();
        const keys = getUsedKeys(parsed);

        for (const key of keys) {
            if (!allowList.includes(key)) {
                throw new errors.IncorrectUsageError({
                    message: 'Cannot filter by ' + key
                });
            }
        }

        try {
            return splitFilter(parsed, ['type']);
        } catch (e) {
            throw new errors.IncorrectUsageError({
                message: e.message
            });
        }
    }

    async getMRR() {
        const results = await this._MemberPaidSubscriptionEvent.findAll({
            aggregateMRRDeltas: true
        });

        const resultsJSON = results.toJSON();

        const cumulativeResults = resultsJSON.reduce((accumulator, result) => {
            if (!accumulator[result.currency]) {
                return {
                    ...accumulator,
                    [result.currency]: [{
                        date: result.date,
                        mrr: result.mrr_delta,
                        currency: result.currency
                    }]
                };
            }
            return {
                ...accumulator,
                [result.currency]: accumulator[result.currency].concat([{
                    date: result.date,
                    mrr: result.mrr_delta + accumulator[result.currency].slice(-1)[0].mrr,
                    currency: result.currency
                }])
            };
        }, {});

        return cumulativeResults;
    }

    async getStatuses() {
        const results = await this._MemberStatusEvent.findAll({
            aggregateStatusCounts: true
        });

        const resultsJSON = results.toJSON();

        const cumulativeResults = resultsJSON.reduce((accumulator, result, index) => {
            if (index === 0) {
                return [{
                    date: result.date,
                    paid: result.paid_delta,
                    comped: result.comped_delta,
                    free: result.free_delta
                }];
            }
            return accumulator.concat([{
                date: result.date,
                paid: result.paid_delta + accumulator[index - 1].paid,
                comped: result.comped_delta + accumulator[index - 1].comped,
                free: result.free_delta + accumulator[index - 1].free
            }]);
        }, []);

        return cumulativeResults;
    }
};