import { Injectable, NotFoundException, ConflictException, BadRequestException } from '@nestjs/common';
import { Prisma, FieldType } from '@prisma/client';
import { PrismaService } from '../prisma';
import { CreateFieldDto, UpdateFieldDto } from './dto';

@Injectable()
export class ProfileFieldsService {
  constructor(private readonly prisma: PrismaService) {}

  /**
   * Generate a URL-friendly slug from the name
   */
  private generateSlug(name: string): string {
    return name
      .toLowerCase()
      .replace(/[^a-z0-9]+/g, '_')
      .replace(/(^_|_$)/g, '');
  }

  /**
   * Create a new profile field
   */
  async create(createFieldDto: CreateFieldDto) {
    const { sectionId, options, rangeConfig, validation, uiConfig, ...rest } = createFieldDto;

    // Verify section exists
    const section = await this.prisma.profileSection.findUnique({
      where: { id: sectionId },
    });

    if (!section) {
      throw new NotFoundException(`Section with ID ${sectionId} not found`);
    }

    // Generate slug
    const slug = this.generateSlug(createFieldDto.name);

    // Check if slug is unique within section
    const existing = await this.prisma.profileField.findUnique({
      where: {
        sectionId_slug: {
          sectionId,
          slug,
        },
      },
    });

    if (existing) {
      throw new ConflictException('A field with this name already exists in this section');
    }

    // Validate options for certain field types
    const requiresOptions = ['SELECT', 'RADIO', 'MULTI_SELECT', 'CHECKBOX'];
    if (requiresOptions.includes(createFieldDto.fieldType) && (!options || options.length === 0)) {
      // CHECKBOX can be a single toggle without options
      if (createFieldDto.fieldType !== 'CHECKBOX') {
        throw new BadRequestException(`Field type ${createFieldDto.fieldType} requires options`);
      }
    }

    // Validate range config for RANGE type
    if (createFieldDto.fieldType === 'RANGE' && !rangeConfig) {
      throw new BadRequestException('RANGE field type requires rangeConfig');
    }

    return this.prisma.profileField.create({
      data: {
        ...rest,
        sectionId,
        slug,
        options: options ? (options as unknown as Prisma.InputJsonValue) : undefined,
        rangeConfig: rangeConfig ? (rangeConfig as unknown as Prisma.InputJsonValue) : undefined,
        validation: validation ? (validation as unknown as Prisma.InputJsonValue) : undefined,
        uiConfig: uiConfig ? (uiConfig as unknown as Prisma.InputJsonValue) : undefined,
      },
      include: {
        section: {
          select: { id: true, name: true, slug: true },
        },
      },
    });
  }

  /**
   * Get all fields, optionally filtered by section
   */
  async findAll(sectionId?: string, includeInactive = false) {
    const where: any = {};

    if (sectionId) {
      where.sectionId = sectionId;
    }

    if (!includeInactive) {
      where.isActive = true;
    }

    return this.prisma.profileField.findMany({
      where,
      orderBy: [{ sortOrder: 'asc' }, { name: 'asc' }],
      include: {
        section: {
          select: { id: true, name: true, slug: true },
        },
      },
    });
  }

  /**
   * Get a single field by ID
   */
  async findOne(id: string) {
    const field = await this.prisma.profileField.findUnique({
      where: { id },
      include: {
        section: {
          select: { id: true, name: true, slug: true },
        },
      },
    });

    if (!field) {
      throw new NotFoundException(`Field with ID ${id} not found`);
    }

    return field;
  }

  /**
   * Update a field
   */
  async update(id: string, updateFieldDto: UpdateFieldDto) {
    const field = await this.findOne(id);

    const data: any = { ...updateFieldDto };

    // If name is being updated, update the slug too
    if (updateFieldDto.name) {
      const newSlug = this.generateSlug(updateFieldDto.name);

      // Check if new slug conflicts within the section
      const existing = await this.prisma.profileField.findFirst({
        where: {
          AND: [
            { id: { not: id } },
            { sectionId: field.sectionId },
            { slug: newSlug },
          ],
        },
      });

      if (existing) {
        throw new ConflictException('A field with this name already exists in this section');
      }

      data.slug = newSlug;
    }

    return this.prisma.profileField.update({
      where: { id },
      data,
      include: {
        section: {
          select: { id: true, name: true, slug: true },
        },
      },
    });
  }

  /**
   * Delete a field
   */
  async remove(id: string) {
    await this.findOne(id);

    // Check if any agents have values for this field
    const valuesCount = await this.prisma.agentProfileFieldValue.count({
      where: { fieldId: id },
    });

    if (valuesCount > 0) {
      throw new ConflictException(
        `Cannot delete field. ${valuesCount} agent(s) have values for this field. Deactivate the field instead.`,
      );
    }

    return this.prisma.profileField.delete({
      where: { id },
    });
  }

  /**
   * Reorder fields within a section
   */
  async reorderFields(sectionId: string, fieldIds: string[]) {
    // Verify section exists
    const section = await this.prisma.profileSection.findUnique({
      where: { id: sectionId },
    });

    if (!section) {
      throw new NotFoundException(`Section with ID ${sectionId} not found`);
    }

    // Update sort order for each field
    const updates = fieldIds.map((fieldId, index) =>
      this.prisma.profileField.update({
        where: { id: fieldId },
        data: { sortOrder: index },
      }),
    );

    await this.prisma.$transaction(updates);

    return this.findAll(sectionId);
  }

  /**
   * Bulk update fields (for drag-drop reordering)
   */
  async bulkUpdateOrder(updates: { id: string; sortOrder: number }[]) {
    const operations = updates.map(({ id, sortOrder }) =>
      this.prisma.profileField.update({
        where: { id },
        data: { sortOrder },
      }),
    );

    await this.prisma.$transaction(operations);

    return { success: true, updated: updates.length };
  }

  /**
   * Get all filterable fields (public endpoint for search filters)
   * Returns fields with CHECKBOX_GROUP, SELECT, MULTI_SELECT types that have options
   * De-duplicates by both slug AND name to handle duplicate fields with different slugs
   */
  async getFilterableFields() {
    const filterableTypes: FieldType[] = [FieldType.CHECKBOX_GROUP, FieldType.SELECT, FieldType.MULTI_SELECT];

    const fields = await this.prisma.profileField.findMany({
      where: {
        isActive: true,
        fieldType: { in: filterableTypes },
        options: { not: Prisma.JsonNull },
      },
      select: {
        id: true,
        name: true,
        slug: true,
        fieldType: true,
        options: true,
        section: {
          select: {
            id: true,
            name: true,
            slug: true,
          },
        },
      },
      orderBy: [
        { section: { sortOrder: 'asc' } },
        { sortOrder: 'asc' },
      ],
    });

    // Group fields by slug to merge options from different sections (same field in different agent types)
    // Also track by normalized name to de-duplicate fields with same name but different slugs
    const mergedFields = new Map<string, {
      slug: string;
      name: string;
      fieldType: string;
      options: { label: string; value: string }[];
    }>();

    // Map normalized names to their primary slug for de-duplication
    const nameToSlugMap = new Map<string, string>();

    for (const field of fields) {
      const fieldOptions = (field.options as { label: string; value: string }[]) || [];
      const normalizedName = field.name.toLowerCase().trim();

      // Check if we already have a field with this name (different slug, same name)
      const existingSlugForName = nameToSlugMap.get(normalizedName);

      if (existingSlugForName) {
        // Merge into existing field with same name
        const existingField = mergedFields.get(existingSlugForName);
        if (existingField) {
          const existingValues = new Set(existingField.options.map(o => o.value));
          for (const opt of fieldOptions) {
            if (!existingValues.has(opt.value)) {
              existingField.options.push(opt);
            }
          }
        }
      } else {
        // Check if we have an existing field with same slug
        const existingFieldBySlug = mergedFields.get(field.slug);

        if (existingFieldBySlug) {
          // Merge options, avoiding duplicates by value
          const existingValues = new Set(existingFieldBySlug.options.map(o => o.value));
          for (const opt of fieldOptions) {
            if (!existingValues.has(opt.value)) {
              existingFieldBySlug.options.push(opt);
            }
          }
        } else {
          // New field - add to both maps
          mergedFields.set(field.slug, {
            slug: field.slug,
            name: field.name,
            fieldType: field.fieldType,
            options: [...fieldOptions],
          });
          nameToSlugMap.set(normalizedName, field.slug);
        }
      }
    }

    return Array.from(mergedFields.values());
  }
}