package service

import (
	"context"
	"spend-sparrow/internal/db"
	"spend-sparrow/internal/types"
	"time"

	"github.com/jmoiron/sqlx"
)

type Dashboard struct {
	db *sqlx.DB
}

func NewDashboard(db *sqlx.DB) *Dashboard {
	return &Dashboard{
		db: db,
	}
}

func (s Dashboard) Summary(ctx context.Context, user *types.User, month time.Time) (*types.DashboardMonthlySummary, error) {
	if user == nil {
		return nil, ErrUnauthorized
	}

	var summary types.DashboardMonthlySummary

	var value *int64
	err := s.db.GetContext(ctx, &value, `
		SELECT SUM(value)
		FROM "transaction"
		WHERE user_id = $1 
			AND treasure_chest_id IS NOT NULL
			AND account_id IS NULL
			AND error IS NULL
			AND date(timestamp, 'start of month') = date($2, 'start of month')`,
		user.Id, month)
	err = db.TransformAndLogDbError(ctx, "dashboard", nil, err)
	if err != nil {
		return nil, err
	}
	if value != nil {
		summary.Savings = *value
	}

	err = s.db.GetContext(ctx, &value, `
		SELECT SUM(value)
		FROM "transaction"
		WHERE user_id = $1
			AND account_id IS NOT NULL
			AND treasure_chest_id IS NULL
			AND error IS NULL
			AND date(timestamp, 'start of month') = date($2, 'start of month')`,
		user.Id, month)
	err = db.TransformAndLogDbError(ctx, "dashboard", nil, err)
	if err != nil {
		return nil, err
	}
	if value != nil {
		summary.Income = *value
	}

	err = s.db.GetContext(ctx, &value, `
		SELECT SUM(value)
		FROM "transaction"
		WHERE user_id = $1
			AND account_id IS NOT NULL
			AND treasure_chest_id IS NOT NULL
			AND error IS NULL
			AND date(timestamp, 'start of month') = date($2, 'start of month')`,
		user.Id, month)
	err = db.TransformAndLogDbError(ctx, "dashboard", nil, err)
	if err != nil {
		return nil, err
	}
	if value != nil {
		summary.Expenses = *value
	}

	summary.Total = summary.Income + summary.Expenses
	summary.Month = month

	err = s.db.GetContext(ctx, &value, `
		SELECT SUM(current_balance)
		FROM treasure_chest
		WHERE user_id = $1`,
		user.Id)
	err = db.TransformAndLogDbError(ctx, "dashboard", nil, err)
	if err != nil {
		return nil, err
	}
	if value != nil {
		summary.SumOfSavings = *value
	}

	err = s.db.GetContext(ctx, &value, `
		SELECT SUM(current_balance)
		FROM account
		WHERE user_id = $1`,
		user.Id)
	err = db.TransformAndLogDbError(ctx, "dashboard", nil, err)
	if err != nil {
		return nil, err
	}
	if value != nil {
		summary.SumOfAccounts = *value
	}

	return &summary, nil
}

func (s Dashboard) MainChart(
	ctx context.Context,
	user *types.User,
) ([]types.DashboardMainChartEntry, error) {
	if user == nil {
		return nil, ErrUnauthorized
	}

	transactions := make([]types.Transaction, 0)
	err := s.db.SelectContext(ctx, &transactions, `
		SELECT *
		FROM "transaction" 
		WHERE user_id = ?
		ORDER BY timestamp`, user.Id)
	err = db.TransformAndLogDbError(ctx, "dashboard Chart", nil, err)
	if err != nil {
		return nil, err
	}

	timeEntries := make([]types.DashboardMainChartEntry, 0)
	var lastEntry *types.DashboardMainChartEntry
	for _, t := range transactions {
		if t.Error != nil {
			continue
		}

		newDay := t.Timestamp.Truncate(24 * time.Hour)
		if lastEntry == nil {
			lastEntry = &types.DashboardMainChartEntry{
				Day:     newDay,
				Value:   0,
				Savings: 0,
			}
		} else if lastEntry.Day != newDay {
			timeEntries = append(timeEntries, *lastEntry)
			lastEntry = &types.DashboardMainChartEntry{
				Day:     newDay,
				Value:   lastEntry.Value,
				Savings: lastEntry.Savings,
			}
		}

		if t.AccountId != nil {
			lastEntry.Value += t.Value
		}
		if t.TreasureChestId != nil {
			lastEntry.Savings += t.Value
		}
	}

	if lastEntry != nil {
		timeEntries = append(timeEntries, *lastEntry)
	}

	return timeEntries, nil
}