import {type Contact, Prisma} from '@plunk/db';
import type {CursorPaginatedResponse, FilterCondition, FilterGroup} from '@plunk/types';
import {toPrismaJson} from '@plunk/types';

import {prisma} from '../database/prisma.js';
import {HttpException} from '../exceptions/index.js';
import {EventService} from './EventService.js';

export class ContactService {
  /**
   * Get all contacts for a project with cursor-based pagination
   * Uses cursor pagination for better performance with large datasets
   */
  public static async list(
    projectId: string,
    limit = 20,
    cursor?: string,
    search?: string,
  ): Promise<CursorPaginatedResponse<Contact>> {
    const where: Prisma.ContactWhereInput = {
      projectId,
      ...(search
        ? {
            email: {
              contains: search,
              mode: 'insensitive' as const,
            },
          }
        : {}),
    };

    // Fetch one extra to determine if there are more results
    // Use composite ordering (createdAt + id) to ensure stable pagination
    // This prevents skipping records when multiple contacts have the same createdAt
    const contacts = await prisma.contact.findMany({
      where,
      take: limit + 1,
      skip: cursor ? 1 : 0,
      cursor: cursor ? {id: cursor} : undefined,
      orderBy: [
        {createdAt: 'desc'},
        {id: 'desc'}, // Secondary sort by id for stable cursor pagination
      ],
    });

    const hasMore = contacts.length > limit;
    const results = hasMore ? contacts.slice(0, -1) : contacts;
    const nextCursor = hasMore ? results[results.length - 1]?.id : undefined;

    // Get total count only on first page for better performance
    const total = !cursor ? await prisma.contact.count({where}) : 0;

    return {
      data: results,
      total,
      cursor: nextCursor,
      hasMore,
    };
  }

  /**
   * Get a single contact by ID
   */
  public static async get(projectId: string, contactId: string): Promise<Contact> {
    const contact = await prisma.contact.findFirst({
      where: {
        id: contactId,
        projectId,
      },
    });

    if (!contact) {
      throw new HttpException(404, 'Contact not found');
    }

    return contact;
  }

  /**
   * Find a contact by email (returns null if not found)
   */
  public static async findByEmail(projectId: string, email: string): Promise<Contact | null> {
    return prisma.contact.findFirst({
      where: {
        projectId,
        email,
      },
    });
  }

  /**
   * Create a new contact
   * Uses unique constraint violation to check for duplicates (more efficient)
   */
  public static async create(
    projectId: string,
    data: {email: string; data?: Prisma.JsonValue; subscribed?: boolean},
  ): Promise<Contact> {
    try {
      return await prisma.contact.create({
        data: {
          projectId,
          email: data.email,
          data: data.data ?? Prisma.JsonNull,
          subscribed: data.subscribed ?? true,
        },
      });
    } catch (error) {
      // Check if this is a unique constraint violation (P2002)
      if (error instanceof Error && 'code' in error && error.code === 'P2002') {
        throw new HttpException(409, 'Contact with this email already exists in this project');
      }
      throw error;
    }
  }

  /**
   * Update a contact
   * Uses unique constraint violation to check for duplicates (more efficient)
   */
  public static async update(
    projectId: string,
    contactId: string,
    data: {email?: string; data?: Prisma.JsonValue; subscribed?: boolean},
  ): Promise<Contact> {
    // First verify contact exists and belongs to project
    const existing = await this.get(projectId, contactId);

    const updateData: Prisma.ContactUpdateInput = {};

    if (data.email !== undefined) {
      updateData.email = data.email;
    }
    if (data.data !== undefined) {
      updateData.data = data.data === null ? Prisma.JsonNull : data.data;
    }
    if (data.subscribed !== undefined) {
      updateData.subscribed = data.subscribed;
    }

    // Track subscription status change
    const isSubscriptionChanging = data.subscribed !== undefined && existing.subscribed !== data.subscribed;
    const wasSubscribed = existing.subscribed;

    try {
      const updated = await prisma.contact.update({
        where: {id: contactId},
        data: updateData,
      });

      // Track subscription event if status changed
      if (isSubscriptionChanging) {
        if (data.subscribed && !wasSubscribed) {
          await EventService.trackEvent(projectId, 'contact.subscribed', contactId);
        } else if (!data.subscribed && wasSubscribed) {
          await EventService.trackEvent(projectId, 'contact.unsubscribed', contactId);
        }
      }

      return updated;
    } catch (error) {
      // Check if this is a unique constraint violation (P2002)
      if (error instanceof Error && 'code' in error && error.code === 'P2002') {
        throw new HttpException(409, 'Contact with this email already exists in this project');
      }
      throw error;
    }
  }

  /**
   * Delete a contact
   */
  public static async delete(projectId: string, contactId: string): Promise<void> {
    // First verify contact exists and belongs to project
    await this.get(projectId, contactId);

    await prisma.contact.delete({
      where: {id: contactId},
    });
  }

  /**
   * Get contact count for a project
   */
  public static async count(projectId: string): Promise<number> {
    return prisma.contact.count({
      where: {projectId},
    });
  }

  /**
   * Upsert a contact (create or update) with metadata merging
   * Supports persistent and non-persistent data fields
   * Reserved fields: plunk_id, plunk_email
   */
  public static async upsert(
    projectId: string,
    email: string,
    data?: Record<string, unknown>,
    subscribed?: boolean,
    defaultSubscribed: boolean = true,
  ): Promise<Contact> {
    // Find existing contact
    const existing = await prisma.contact.findFirst({
      where: {
        projectId,
        email,
      },
    });

    // Process data to merge with existing data
    let mergedData: Record<string, unknown> = {};

    if (existing?.data && typeof existing.data === 'object' && !Array.isArray(existing.data)) {
      // Start with existing data
      mergedData = {...existing.data};
    }

    // Merge new data (if provided)
    if (data) {
      for (const [key, value] of Object.entries(data)) {
        // Skip reserved system-generated fields
        // These fields are dynamically added during template rendering and cannot be overridden
        const reservedFields = [
          'plunk_id',
          'plunk_email',
          'id',
          'email',
          'unsubscribeUrl',
          'subscribeUrl',
          'manageUrl',
        ];
        if (reservedFields.includes(key)) {
          continue;
        }

        // Validate locale field (special user-settable field)
        // Only validate type - any locale string is accepted since we default to English if unsupported
        if (key === 'locale') {
          if (value !== null && value !== undefined && typeof value !== 'string') {
            throw new HttpException(400, 'Locale must be a string');
          }
        }

        // Handle non-persistent data format: { value: "...", persistent: false }
        if (
          typeof value === 'object' &&
          value !== null &&
          'value' in value &&
          'persistent' in value &&
          value.persistent === false
        ) {
          // Non-persistent fields are not stored in contact data
          // They would be used only for the current operation (like email template rendering)
          continue;
        }

        // Store the value
        mergedData[key] = value;
      }
    }

    if (existing) {
      // Track subscription status change
      const isSubscriptionChanging = subscribed !== undefined && existing.subscribed !== subscribed;
      const wasSubscribed = existing.subscribed;

      const updated = await prisma.contact.update({
        where: {id: existing.id},
        data: {
          data: Object.keys(mergedData).length > 0 ? toPrismaJson(mergedData) : Prisma.JsonNull,
          ...(subscribed !== undefined ? {subscribed} : {}),
        },
      });

      // Track subscription event if status changed
      if (isSubscriptionChanging) {
        if (subscribed && !wasSubscribed) {
          await EventService.trackEvent(projectId, 'contact.subscribed', updated.id);
        } else if (!subscribed && wasSubscribed) {
          await EventService.trackEvent(projectId, 'contact.unsubscribed', updated.id);
        }
      }

      return updated;
    } else {
      return prisma.contact.create({
        data: {
          projectId,
          email,
          data: Object.keys(mergedData).length > 0 ? toPrismaJson(mergedData) : Prisma.JsonNull,
          subscribed: subscribed ?? defaultSubscribed,
        },
      });
    }
  }

  /**
   * Get the full merged data for a contact including non-persistent fields
   * This is useful for template rendering
   */
  public static getMergedData(contact: Contact, temporaryData?: Record<string, unknown>): Record<string, unknown> {
    const mergedData: Record<string, unknown> = {
      plunk_id: contact.id,
      plunk_email: contact.email,
    };

    // Add contact's persistent data
    if (contact.data && typeof contact.data === 'object' && !Array.isArray(contact.data)) {
      Object.assign(mergedData, contact.data);
    }

    // Explicitly expose locale as a predefined field (available in templates)
    // This ensures locale is always accessible even if not in contact.data
    if (mergedData.locale === undefined) {
      mergedData.locale = null;
    }

    // Add temporary (non-persistent) data
    if (temporaryData) {
      for (const [key, value] of Object.entries(temporaryData)) {
        // Skip reserved system-generated fields
        const reservedFields = ['plunk_id', 'plunk_email', 'email', 'unsubscribeUrl', 'subscribeUrl', 'manageUrl'];
        if (reservedFields.includes(key)) {
          continue;
        }

        // Handle non-persistent data format: { value: "...", persistent: false }
        if (
          typeof value === 'object' &&
          value !== null &&
          'value' in value &&
          'persistent' in value &&
          value.persistent === false
        ) {
          mergedData[key] = value.value;
        } else {
          mergedData[key] = value;
        }
      }
    }

    return mergedData;
  }

  /**
   * PUBLIC: Get a contact by ID (no project authentication required)
   * This is used for public-facing pages like unsubscribe
   */
  public static async getById(contactId: string): Promise<Contact> {
    const contact = await prisma.contact.findUnique({
      where: {id: contactId},
    });

    if (!contact) {
      throw new HttpException(404, 'Contact not found');
    }

    return contact;
  }

  /**
   * Get project by contact ID
   * Used to fetch project settings for public endpoints
   */
  public static async getProjectByContactId(contactId: string): Promise<{language: string} | null> {
    const contact = await prisma.contact.findUnique({
      where: {id: contactId},
      select: {
        project: {
          select: {
            language: true,
          },
        },
      },
    });

    return contact?.project || null;
  }

  /**
   * PUBLIC: Subscribe a contact
   */
  public static async subscribe(contactId: string): Promise<Contact> {
    const contact = await prisma.contact.update({
      where: {id: contactId},
      data: {subscribed: true},
    });

    // Track subscription event
    await EventService.trackEvent(contact.projectId, 'contact.subscribed', contactId);

    return contact;
  }

  /**
   * PUBLIC: Unsubscribe a contact
   */
  public static async unsubscribe(contactId: string): Promise<Contact> {
    const contact = await prisma.contact.update({
      where: {id: contactId},
      data: {subscribed: false},
    });

    // Track unsubscription event
    await EventService.trackEvent(contact.projectId, 'contact.unsubscribed', contactId);

    return contact;
  }

  /**
   * Get all available contact fields for a project
   * Returns both standard fields and custom fields from the data JSON column
   * Now includes type information inferred from actual data
   *
   * @param projectId - The project ID to filter contacts
   * @returns Array of field objects with name and type
   */
  public static async getAvailableFields(
    projectId: string,
  ): Promise<Array<{field: string; type: 'string' | 'number' | 'boolean' | 'date'; coverage: number}>> {
    // Get total contact count for coverage calculation
    const totalContacts = await prisma.contact.count({
      where: {projectId},
    });

    // Standard fields with known types (always 100% coverage)
    const standardFields = [
      {field: 'email', type: 'string' as const, coverage: 100},
      {field: 'subscribed', type: 'boolean' as const, coverage: 100},
      {field: 'createdAt', type: 'date' as const, coverage: 100},
      {field: 'updatedAt', type: 'date' as const, coverage: 100},
    ];

    // Get custom fields from the data JSON column with type inference and coverage
    // Use raw SQL to extract all keys, sample values, and contact counts from the JSON data column
    const result = await prisma.$queryRaw<
      Array<{key: string; sample_value: string; json_type: string; contact_count: bigint}>
    >`
      WITH field_keys AS (
        SELECT DISTINCT jsonb_object_keys(data) as key
        FROM contacts
        WHERE
          "projectId" = ${projectId}
          AND data IS NOT NULL
          AND jsonb_typeof(data) = 'object'
      ),
      field_samples AS (
        SELECT
          fk.key,
          jsonb_typeof(c.data->fk.key) as json_type,
          (c.data->>fk.key) as sample_value
        FROM field_keys fk
        CROSS JOIN LATERAL (
          SELECT data
          FROM contacts
          WHERE
            "projectId" = ${projectId}
            AND data ? fk.key
            AND data->fk.key IS NOT NULL
          LIMIT 1
        ) c
      ),
      field_counts AS (
        SELECT
          fk.key,
          COUNT(*) as contact_count
        FROM field_keys fk
        JOIN contacts c ON c."projectId" = ${projectId}
          AND c.data ? fk.key
          AND c.data->fk.key IS NOT NULL
        GROUP BY fk.key
      )
      SELECT
        fs.key,
        fs.sample_value,
        fs.json_type,
        fc.contact_count
      FROM field_samples fs
      JOIN field_counts fc ON fc.key = fs.key
    `;

    // Infer types from JSON types and sample values, calculate coverage
    const customFields = result.map(row => {
      let type: 'string' | 'number' | 'boolean' | 'date' = 'string';

      // PostgreSQL jsonb_typeof returns: "object", "array", "string", "number", "boolean", "null"
      if (row.json_type === 'boolean') {
        type = 'boolean';
      } else if (row.json_type === 'number') {
        type = 'number';
      } else if (row.json_type === 'string' && row.sample_value) {
        // Try to detect dates (ISO 8601 format)
        const dateRegex = /^\d{4}-\d{2}-\d{2}(T\d{2}:\d{2}:\d{2}(\.\d{3})?Z?)?$/;
        if (dateRegex.test(row.sample_value)) {
          type = 'date';
        }
      }

      // Calculate coverage percentage
      const contactCount = Number(row.contact_count);
      const coverage = totalContacts > 0 ? Math.round((contactCount / totalContacts) * 100) : 0;

      return {
        field: `data.${row.key}`,
        type,
        coverage,
      };
    });

    return [...standardFields, ...customFields].sort((a, b) => a.field.localeCompare(b.field));
  }

  /**
   * Get unique values for a contact field
   * Optimized for large datasets (1M+ contacts) - limits results and uses efficient queries
   *
   * @param projectId - The project ID to filter contacts
   * @param field - The field path (e.g., "subscribed", "email", "data.plan", "data.firstName")
   * @param limit - Maximum number of unique values to return (default: 100)
   * @returns Array of unique values, sorted alphabetically
   */
  public static async getUniqueFieldValues(
    projectId: string,
    field: string,
    limit = 100,
  ): Promise<Array<string | number | boolean>> {
    if (field === 'subscribed') {
      // Boolean field - return both possible values
      return [true, false];
    }

    if (field === 'email') {
      // Email is not useful for dropdowns, return empty
      return [];
    }

    // Handle JSON data fields (e.g., "data.plan" or just "plan")
    const jsonField = field.startsWith('data.') ? field.substring(5) : field;

    // Use raw SQL for performance with large datasets
    // Extract unique values from the JSON field using PostgreSQL's JSON operators
    const result = await prisma.$queryRaw<Array<{value: unknown}>>`
      SELECT DISTINCT
        data->>${jsonField} as value
      FROM contacts
      WHERE
        "projectId" = ${projectId}
        AND data ? ${jsonField}
        AND data->>${jsonField} IS NOT NULL
        AND data->>${jsonField} != ''
      ORDER BY value
      LIMIT ${limit}
    `;

    // Parse and return values, handling different data types
    return result
      .map(row => {
        const value = String(row.value);

        // Try to parse as boolean
        if (value === 'true') return true;
        if (value === 'false') return false;

        // Try to parse as number
        const numValue = Number(value);
        if (!isNaN(numValue) && value.trim() !== '') {
          return numValue;
        }

        // Return as string
        return value;
      })
      .filter(v => v !== null && v !== undefined);
  }

  /**
   * Check if a contact field is used in any segments or campaigns
   * Returns usage information including which segments/campaigns use the field
   *
   * @param projectId - The project ID
   * @param field - The field to check (e.g., "data.plan", "email", "subscribed")
   * @returns Usage information
   */
  public static async getFieldUsage(
    projectId: string,
    field: string,
  ): Promise<{
    usedInSegments: Array<{id: string; name: string}>;
    usedInCampaigns: Array<{id: string; name: string}>;
    contactCount: number;
    canDelete: boolean;
  }> {
    // Get all segments for the project
    const segments = await prisma.segment.findMany({
      where: {projectId},
      select: {id: true, name: true, condition: true},
    });

    // Check which segments use this field
    const usedInSegments = segments.filter(segment => {
      const condition = segment.condition as FilterCondition | null;
      return this.fieldUsedInCondition(field, condition);
    });

    // For now, we'll check if campaigns use the field in their subject or body
    // This is a simplified check - you might want to enhance this based on your campaign structure
    const usedInCampaigns: Array<{id: string; name: string}> = [];

    // Count contacts that have this field (for data fields)
    let contactCount = 0;
    if (field.startsWith('data.')) {
      const jsonField = field.substring(5);
      const result = await prisma.$queryRaw<Array<{count: bigint}>>`
        SELECT COUNT(*) as count
        FROM contacts
        WHERE
          "projectId" = ${projectId}
          AND data ? ${jsonField}
          AND data->${jsonField} IS NOT NULL
      `;
      contactCount = Number(result[0]?.count || 0);
    } else if (field === 'email' || field === 'subscribed' || field === 'createdAt' || field === 'updatedAt') {
      // Standard fields exist on all contacts
      const result = await prisma.contact.count({where: {projectId}});
      contactCount = result;
    }

    const canDelete = usedInSegments.length === 0 && usedInCampaigns.length === 0;

    return {
      usedInSegments: usedInSegments.map(s => ({id: s.id, name: s.name})),
      usedInCampaigns,
      contactCount,
      canDelete,
    };
  }

  /**
   * Delete a custom field from all contacts
   * WARNING: This is destructive and cannot be undone
   * Should only be called after verifying the field is not in use
   *
   * @param projectId - The project ID
   * @param field - The field to delete (must be a data.* field)
   */
  public static async deleteField(projectId: string, field: string): Promise<{deletedFrom: number}> {
    // Only allow deleting custom data fields
    if (!field.startsWith('data.')) {
      throw new HttpException(400, 'Can only delete custom data fields (data.*)');
    }

    // Check if field is in use
    const usage = await this.getFieldUsage(projectId, field);
    if (!usage.canDelete) {
      throw new HttpException(
        400,
        `Cannot delete field: used in ${usage.usedInSegments.length} segment(s) and ${usage.usedInCampaigns.length} campaign(s)`,
      );
    }

    const jsonField = field.substring(5);

    // Delete the field from all contacts using raw SQL
    // PostgreSQL's `-` operator removes a key from a JSON object
    const result = await prisma.$executeRaw`
      UPDATE contacts
      SET data = data - ${jsonField}
      WHERE
        "projectId" = ${projectId}
        AND data ? ${jsonField}
    `;

    return {deletedFrom: result};
  }

  /**
   * Bulk subscribe contacts
   * Updates multiple contacts to subscribed=true in batches
   */
  public static async bulkSubscribe(projectId: string, contactIds: string[]): Promise<{updated: number}> {
    // Verify all contacts belong to this project
    const contacts = await prisma.contact.findMany({
      where: {
        id: {in: contactIds},
        projectId,
      },
      select: {id: true, subscribed: true},
    });

    const validIds = contacts.map(c => c.id);

    if (validIds.length === 0) {
      return {updated: 0};
    }

    // Only update contacts that are currently unsubscribed
    const unsubscribedIds = contacts.filter(c => !c.subscribed).map(c => c.id);

    if (unsubscribedIds.length === 0) {
      return {updated: 0};
    }

    // Update in a single query for performance
    const result = await prisma.contact.updateMany({
      where: {
        id: {in: unsubscribedIds},
        projectId,
      },
      data: {
        subscribed: true,
      },
    });

    // Track events for changed contacts sequentially to avoid database deadlocks
    // Process in background to avoid blocking the API response
    this.trackEventsSequentially(projectId, 'contact.subscribed', unsubscribedIds).catch(error => {
      // Silently ignore errors in tests due to cleanup race conditions
      if (process.env.NODE_ENV !== 'test') {
        console.error('[ContactService] Failed to track bulk subscribe events:', error);
      }
    });

    return {updated: result.count};
  }

  /**
   * Bulk unsubscribe contacts
   */
  public static async bulkUnsubscribe(projectId: string, contactIds: string[]): Promise<{updated: number}> {
    const contacts = await prisma.contact.findMany({
      where: {
        id: {in: contactIds},
        projectId,
      },
      select: {id: true, subscribed: true},
    });

    const validIds = contacts.map(c => c.id);

    if (validIds.length === 0) {
      return {updated: 0};
    }

    // Only update contacts that are currently subscribed
    const subscribedIds = contacts.filter(c => c.subscribed).map(c => c.id);

    if (subscribedIds.length === 0) {
      return {updated: 0};
    }

    const result = await prisma.contact.updateMany({
      where: {
        id: {in: subscribedIds},
        projectId,
      },
      data: {
        subscribed: false,
      },
    });

    // Track events for changed contacts sequentially to avoid database deadlocks
    // Process in background to avoid blocking the API response
    this.trackEventsSequentially(projectId, 'contact.unsubscribed', subscribedIds).catch(error => {
      // Silently ignore errors in tests due to cleanup race conditions
      if (process.env.NODE_ENV !== 'test') {
        console.error('[ContactService] Failed to track bulk unsubscribe events:', error);
      }
    });

    return {updated: result.count};
  }

  /**
   * Bulk delete contacts
   */
  public static async bulkDelete(projectId: string, contactIds: string[]): Promise<{deleted: number}> {
    const result = await prisma.contact.deleteMany({
      where: {
        id: {in: contactIds},
        projectId,
      },
    });

    return {deleted: result.count};
  }

  /**
   * Helper: Check if a field is used in a filter condition (recursive)
   */
  private static fieldUsedInCondition(field: string, condition: FilterCondition | null): boolean {
    if (!condition || typeof condition !== 'object') {
      return false;
    }

    // Check groups in the condition
    if (Array.isArray(condition.groups)) {
      for (const group of condition.groups) {
        if (this.fieldUsedInGroup(field, group)) {
          return true;
        }
      }
    }

    return false;
  }

  /**
   * Helper: Check if a field is used in a filter group (recursive)
   */
  private static fieldUsedInGroup(field: string, group: FilterGroup): boolean {
    if (!group || typeof group !== 'object') {
      return false;
    }

    // Check filters in the group
    if (Array.isArray(group.filters)) {
      for (const filter of group.filters) {
        if (filter.field === field) {
          return true;
        }
      }
    }

    // Check nested conditions
    if (group.conditions) {
      return this.fieldUsedInCondition(field, group.conditions);
    }

    return false;
  }

  /**
   * Track events sequentially to avoid database deadlocks
   * Processes events one at a time with error handling
   *
   * @private
   */
  private static async trackEventsSequentially(
    projectId: string,
    eventName: string,
    contactIds: string[],
  ): Promise<void> {
    for (const contactId of contactIds) {
      try {
        await EventService.trackEvent(projectId, eventName, contactId);
      } catch (error) {
        // Log error but continue processing remaining events
        // Suppress logging in test environments to reduce noise from cleanup race conditions
        if (process.env.NODE_ENV !== 'test') {
          console.error(`[ContactService] Failed to track event ${eventName} for contact ${contactId}:`, error);
        }
      }
    }
  }
}