import { Injectable, NotFoundException, BadRequestException } from '@nestjs/common';
import { TenantService } from '../../database/tenant.service';

@Injectable()
export class BoardPlanningService {
  constructor(private tenant: TenantService) {}

  // ── Scenarios ──

  async listScenarios(type?: string) {
    let sql = `
      SELECT bs.*,
        (SELECT COUNT(*) FROM scenario_investments si WHERE si.scenario_id = bs.id) as investment_count,
        (SELECT COALESCE(SUM(si.principal), 0) FROM scenario_investments si WHERE si.scenario_id = bs.id) as total_principal,
        (SELECT COUNT(*) FROM scenario_assessments sa WHERE sa.scenario_id = bs.id) as assessment_count
      FROM board_scenarios bs
      WHERE bs.status != 'archived'
    `;
    const params: any[] = [];
    if (type) {
      params.push(type);
      sql += ` AND bs.scenario_type = $${params.length}`;
    }
    sql += ' ORDER BY bs.updated_at DESC';
    return this.tenant.query(sql, params);
  }

  async getScenario(id: string) {
    const rows = await this.tenant.query('SELECT * FROM board_scenarios WHERE id = $1', [id]);
    if (!rows.length) throw new NotFoundException('Scenario not found');
    const scenario = rows[0];

    const investments = await this.tenant.query(
      'SELECT * FROM scenario_investments WHERE scenario_id = $1 ORDER BY sort_order, purchase_date',
      [id],
    );
    const assessments = await this.tenant.query(
      'SELECT * FROM scenario_assessments WHERE scenario_id = $1 ORDER BY sort_order, effective_date',
      [id],
    );

    return { ...scenario, investments, assessments };
  }

  async createScenario(dto: any, userId: string) {
    const rows = await this.tenant.query(
      `INSERT INTO board_scenarios (name, description, scenario_type, projection_months, created_by)
       VALUES ($1, $2, $3, $4, $5) RETURNING *`,
      [dto.name, dto.description || null, dto.scenarioType, dto.projectionMonths || 36, userId],
    );
    return rows[0];
  }

  async updateScenario(id: string, dto: any) {
    await this.getScenarioRow(id);
    const rows = await this.tenant.query(
      `UPDATE board_scenarios SET
        name = COALESCE($2, name),
        description = COALESCE($3, description),
        status = COALESCE($4, status),
        projection_months = COALESCE($5, projection_months),
        updated_at = NOW()
       WHERE id = $1 RETURNING *`,
      [id, dto.name, dto.description, dto.status, dto.projectionMonths],
    );
    return rows[0];
  }

  async deleteScenario(id: string) {
    await this.getScenarioRow(id);
    await this.tenant.query(
      `UPDATE board_scenarios SET status = 'archived', updated_at = NOW() WHERE id = $1`,
      [id],
    );
  }

  // ── Scenario Investments ──

  async listInvestments(scenarioId: string) {
    return this.tenant.query(
      'SELECT * FROM scenario_investments WHERE scenario_id = $1 ORDER BY sort_order, purchase_date',
      [scenarioId],
    );
  }

  async addInvestment(scenarioId: string, dto: any) {
    await this.getScenarioRow(scenarioId);
    const rows = await this.tenant.query(
      `INSERT INTO scenario_investments
        (scenario_id, source_recommendation_id, label, investment_type, fund_type,
         principal, interest_rate, term_months, institution, purchase_date, maturity_date,
         auto_renew, notes, sort_order)
       VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14)
       RETURNING *`,
      [
        scenarioId, dto.sourceRecommendationId || null, dto.label,
        dto.investmentType || null, dto.fundType,
        dto.principal, dto.interestRate || null, dto.termMonths || null,
        dto.institution || null, dto.purchaseDate || null, dto.maturityDate || null,
        dto.autoRenew || false, dto.notes || null, dto.sortOrder || 0,
      ],
    );
    await this.invalidateProjectionCache(scenarioId);
    return rows[0];
  }

  async addInvestmentFromRecommendation(scenarioId: string, dto: any) {
    await this.getScenarioRow(scenarioId);

    // If the recommendation has components (e.g. CD ladder with multiple CDs), create one row per component
    const components = dto.components as any[] | undefined;
    if (components && Array.isArray(components) && components.length > 0) {
      const results: any[] = [];
      for (let i = 0; i < components.length; i++) {
        const comp = components[i];
        const rows = await this.tenant.query(
          `INSERT INTO scenario_investments
            (scenario_id, source_recommendation_id, label, investment_type, fund_type,
             principal, interest_rate, term_months, institution, notes, sort_order)
           VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11)
           RETURNING *`,
          [
            scenarioId, dto.sourceRecommendationId || null,
            comp.label || `${dto.title || 'AI Recommendation'} - Part ${i + 1}`,
            comp.investment_type || dto.investmentType || null,
            dto.fundType || 'reserve',
            comp.amount || 0, comp.rate || null,
            comp.term_months || null, comp.bank_name || dto.bankName || null,
            dto.rationale || dto.notes || null,
            i,
          ],
        );
        results.push(rows[0]);
      }
      await this.invalidateProjectionCache(scenarioId);
      return results;
    }

    // Single investment (no components)
    const rows = await this.tenant.query(
      `INSERT INTO scenario_investments
        (scenario_id, source_recommendation_id, label, investment_type, fund_type,
         principal, interest_rate, term_months, institution, notes)
       VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)
       RETURNING *`,
      [
        scenarioId, dto.sourceRecommendationId || null,
        dto.title || dto.label || 'AI Recommendation',
        dto.investmentType || null, dto.fundType || 'reserve',
        dto.suggestedAmount || 0, dto.suggestedRate || null,
        dto.termMonths || null, dto.bankName || null,
        dto.rationale || dto.notes || null,
      ],
    );
    await this.invalidateProjectionCache(scenarioId);
    return rows[0];
  }

  async updateInvestment(id: string, dto: any) {
    const inv = await this.getInvestmentRow(id);
    const rows = await this.tenant.query(
      `UPDATE scenario_investments SET
        label = COALESCE($2, label),
        investment_type = COALESCE($3, investment_type),
        fund_type = COALESCE($4, fund_type),
        principal = COALESCE($5, principal),
        interest_rate = COALESCE($6, interest_rate),
        term_months = COALESCE($7, term_months),
        institution = COALESCE($8, institution),
        purchase_date = COALESCE($9, purchase_date),
        maturity_date = COALESCE($10, maturity_date),
        auto_renew = COALESCE($11, auto_renew),
        notes = COALESCE($12, notes),
        sort_order = COALESCE($13, sort_order),
        updated_at = NOW()
       WHERE id = $1 RETURNING *`,
      [
        id, dto.label, dto.investmentType, dto.fundType,
        dto.principal, dto.interestRate, dto.termMonths,
        dto.institution, dto.purchaseDate, dto.maturityDate,
        dto.autoRenew, dto.notes, dto.sortOrder,
      ],
    );
    await this.invalidateProjectionCache(inv.scenario_id);
    return rows[0];
  }

  async removeInvestment(id: string) {
    const inv = await this.getInvestmentRow(id);
    await this.tenant.query('DELETE FROM scenario_investments WHERE id = $1', [id]);
    await this.invalidateProjectionCache(inv.scenario_id);
  }

  // ── Scenario Assessments ──

  async listAssessments(scenarioId: string) {
    return this.tenant.query(
      'SELECT * FROM scenario_assessments WHERE scenario_id = $1 ORDER BY sort_order, effective_date',
      [scenarioId],
    );
  }

  async addAssessment(scenarioId: string, dto: any) {
    await this.getScenarioRow(scenarioId);
    const rows = await this.tenant.query(
      `INSERT INTO scenario_assessments
        (scenario_id, change_type, label, target_fund, percentage_change,
         flat_amount_change, special_total, special_per_unit, special_installments,
         effective_date, end_date, applies_to_group_id, notes, sort_order)
       VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14)
       RETURNING *`,
      [
        scenarioId, dto.changeType, dto.label, dto.targetFund || 'operating',
        dto.percentageChange || null, dto.flatAmountChange || null,
        dto.specialTotal || null, dto.specialPerUnit || null,
        dto.specialInstallments || 1, dto.effectiveDate,
        dto.endDate || null, dto.appliesToGroupId || null,
        dto.notes || null, dto.sortOrder || 0,
      ],
    );
    await this.invalidateProjectionCache(scenarioId);
    return rows[0];
  }

  async updateAssessment(id: string, dto: any) {
    const asmt = await this.getAssessmentRow(id);
    const rows = await this.tenant.query(
      `UPDATE scenario_assessments SET
        change_type = COALESCE($2, change_type),
        label = COALESCE($3, label),
        target_fund = COALESCE($4, target_fund),
        percentage_change = COALESCE($5, percentage_change),
        flat_amount_change = COALESCE($6, flat_amount_change),
        special_total = COALESCE($7, special_total),
        special_per_unit = COALESCE($8, special_per_unit),
        special_installments = COALESCE($9, special_installments),
        effective_date = COALESCE($10, effective_date),
        end_date = COALESCE($11, end_date),
        applies_to_group_id = COALESCE($12, applies_to_group_id),
        notes = COALESCE($13, notes),
        sort_order = COALESCE($14, sort_order),
        updated_at = NOW()
       WHERE id = $1 RETURNING *`,
      [
        id, dto.changeType, dto.label, dto.targetFund,
        dto.percentageChange, dto.flatAmountChange,
        dto.specialTotal, dto.specialPerUnit, dto.specialInstallments,
        dto.effectiveDate, dto.endDate, dto.appliesToGroupId,
        dto.notes, dto.sortOrder,
      ],
    );
    await this.invalidateProjectionCache(asmt.scenario_id);
    return rows[0];
  }

  async removeAssessment(id: string) {
    const asmt = await this.getAssessmentRow(id);
    await this.tenant.query('DELETE FROM scenario_assessments WHERE id = $1', [id]);
    await this.invalidateProjectionCache(asmt.scenario_id);
  }

  // ── Execute Investment (Story 1D) ──

  async executeInvestment(investmentId: string, executionDate: string, userId: string) {
    const inv = await this.getInvestmentRow(investmentId);
    if (inv.executed_investment_id) {
      throw new BadRequestException('This investment has already been executed');
    }

    // 1. Create real investment_accounts record
    const invRows = await this.tenant.query(
      `INSERT INTO investment_accounts
        (name, institution, investment_type, fund_type, principal, interest_rate,
         maturity_date, purchase_date, current_value, notes, is_active)
       VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, true)
       RETURNING *`,
      [
        inv.label, inv.institution, inv.investment_type || 'cd',
        inv.fund_type, inv.principal, inv.interest_rate || 0,
        inv.maturity_date, executionDate, inv.principal,
        `Executed from scenario investment. ${inv.notes || ''}`.trim(),
      ],
    );
    const realInvestment = invRows[0];

    // 2. Create journal entry at the execution date
    const entryDate = new Date(executionDate);
    const year = entryDate.getFullYear();
    const month = entryDate.getMonth() + 1;

    const periods = await this.tenant.query(
      'SELECT id FROM fiscal_periods WHERE year = $1 AND month = $2',
      [year, month],
    );
    if (periods.length) {
      const primaryRows = await this.tenant.query(
        `SELECT id, name FROM accounts WHERE is_primary = true AND fund_type = $1 AND is_active = true LIMIT 1`,
        [inv.fund_type],
      );
      const equityAccountNumber = inv.fund_type === 'reserve' ? '3100' : '3000';
      const equityRows = await this.tenant.query(
        'SELECT id FROM accounts WHERE account_number = $1',
        [equityAccountNumber],
      );

      if (primaryRows.length && equityRows.length) {
        const memo = `Transfer to investment: ${inv.label}`;
        const jeRows = await this.tenant.query(
          `INSERT INTO journal_entries (entry_date, description, entry_type, fiscal_period_id, is_posted, posted_at, created_by)
           VALUES ($1, $2, 'transfer', $3, true, NOW(), $4)
           RETURNING *`,
          [executionDate, memo, periods[0].id, userId],
        );
        const je = jeRows[0];
        // Credit primary asset account (reduces cash)
        await this.tenant.query(
          `INSERT INTO journal_entry_lines (journal_entry_id, account_id, debit, credit, memo)
           VALUES ($1, $2, 0, $3, $4)`,
          [je.id, primaryRows[0].id, inv.principal, memo],
        );
        // Debit equity offset account
        await this.tenant.query(
          `INSERT INTO journal_entry_lines (journal_entry_id, account_id, debit, credit, memo)
           VALUES ($1, $2, $3, 0, $4)`,
          [je.id, equityRows[0].id, inv.principal, memo],
        );
      }
    }

    // 3. Link back to scenario investment
    await this.tenant.query(
      `UPDATE scenario_investments SET executed_investment_id = $1, updated_at = NOW() WHERE id = $2`,
      [realInvestment.id, investmentId],
    );

    await this.invalidateProjectionCache(inv.scenario_id);
    return realInvestment;
  }

  // ── Helpers ──

  private async getScenarioRow(id: string) {
    const rows = await this.tenant.query('SELECT * FROM board_scenarios WHERE id = $1', [id]);
    if (!rows.length) throw new NotFoundException('Scenario not found');
    return rows[0];
  }

  private async getInvestmentRow(id: string) {
    const rows = await this.tenant.query('SELECT * FROM scenario_investments WHERE id = $1', [id]);
    if (!rows.length) throw new NotFoundException('Scenario investment not found');
    return rows[0];
  }

  private async getAssessmentRow(id: string) {
    const rows = await this.tenant.query('SELECT * FROM scenario_assessments WHERE id = $1', [id]);
    if (!rows.length) throw new NotFoundException('Scenario assessment not found');
    return rows[0];
  }

  async invalidateProjectionCache(scenarioId: string) {
    await this.tenant.query(
      `UPDATE board_scenarios SET projection_cache = NULL, projection_cached_at = NULL, updated_at = NOW() WHERE id = $1`,
      [scenarioId],
    );
  }
}