package store

import (
	"context"
	"database/sql"
	"errors"
	"fmt"

	"gitea.stevedudenhoeffer.com/steve/pansy/internal/domain"
)

// seedLotColumns lists seed_lots columns in the order scanSeedLot expects.
const seedLotColumns = `id, owner_id, plant_id, vendor, source_url, sku, lot_code,
	purchased_at, packed_for_year, quantity, unit, cost_cents, germination_pct, notes,
	version, created_at, updated_at`

func scanSeedLot(s scanner) (*domain.SeedLot, error) {
	var l domain.SeedLot
	if err := s.Scan(
		&l.ID, &l.OwnerID, &l.PlantID, &l.Vendor, &l.SourceURL, &l.SKU, &l.LotCode,
		&l.PurchasedAt, &l.PackedForYear, &l.Quantity, &l.Unit, &l.CostCents,
		&l.GerminationPct, &l.Notes, &l.Version, &l.CreatedAt, &l.UpdatedAt,
	); err != nil {
		return nil, err
	}
	return &l, nil
}

// CreateSeedLot inserts a lot (fields already validated by the service).
func (d *DB) CreateSeedLot(ctx context.Context, l *domain.SeedLot) (*domain.SeedLot, error) {
	created, err := scanSeedLot(d.sql.QueryRowContext(ctx,
		`INSERT INTO seed_lots
		   (owner_id, plant_id, vendor, source_url, sku, lot_code, purchased_at,
		    packed_for_year, quantity, unit, cost_cents, germination_pct, notes)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
		 RETURNING `+seedLotColumns,
		l.OwnerID, l.PlantID, l.Vendor, l.SourceURL, l.SKU, l.LotCode, l.PurchasedAt,
		l.PackedForYear, l.Quantity, l.Unit, l.CostCents, l.GerminationPct, l.Notes,
	))
	if err != nil {
		return nil, fmt.Errorf("store: insert seed lot: %w", err)
	}
	return created, nil
}

// GetSeedLot returns a lot by id, or domain.ErrNotFound. Ownership is the
// service's check, not this one's.
func (d *DB) GetSeedLot(ctx context.Context, id int64) (*domain.SeedLot, error) {
	l, err := scanSeedLot(d.sql.QueryRowContext(ctx,
		`SELECT `+seedLotColumns+` FROM seed_lots WHERE id = ?`, id))
	if errors.Is(err, sql.ErrNoRows) {
		return nil, domain.ErrNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("store: get seed lot: %w", err)
	}
	return l, nil
}

// ListSeedLotsForOwner returns every lot the actor owns, newest purchase first
// (undated lots last), then by id. Optionally narrowed to one plant. Always a
// non-nil slice.
func (d *DB) ListSeedLotsForOwner(ctx context.Context, ownerID int64, plantID *int64) ([]domain.SeedLot, error) {
	query := `SELECT ` + seedLotColumns + ` FROM seed_lots WHERE owner_id = ?`
	args := []any{ownerID}
	if plantID != nil {
		query += ` AND plant_id = ?`
		args = append(args, *plantID)
	}
	// NULL purchased_at sorts last: an undated lot is the least useful to see first.
	query += ` ORDER BY purchased_at IS NULL, purchased_at DESC, id DESC`

	rows, err := d.sql.QueryContext(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("store: list seed lots: %w", err)
	}
	defer rows.Close()

	lots := []domain.SeedLot{}
	for rows.Next() {
		l, err := scanSeedLot(rows)
		if err != nil {
			return nil, fmt.Errorf("store: scan seed lot: %w", err)
		}
		lots = append(lots, *l)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("store: iterate seed lots: %w", err)
	}
	return lots, nil
}

// UpdateSeedLot applies a version-guarded update of every mutable column (the
// service merges partial patches onto the current row first). Same contract as
// the other mutable resources: the updated row, or (current, ErrVersionConflict).
// plant_id and owner_id are immutable — re-pointing a purchase at a different
// variety or user would rewrite history rather than correct it.
func (d *DB) UpdateSeedLot(ctx context.Context, l *domain.SeedLot) (*domain.SeedLot, error) {
	updated, err := scanSeedLot(d.sql.QueryRowContext(ctx,
		`UPDATE seed_lots
		    SET vendor = ?, source_url = ?, sku = ?, lot_code = ?, purchased_at = ?,
		        packed_for_year = ?, quantity = ?, unit = ?, cost_cents = ?,
		        germination_pct = ?, notes = ?,
		        version = version + 1,
		        updated_at = strftime('%Y-%m-%dT%H:%M:%SZ', 'now')
		  WHERE id = ? AND version = ?
		  RETURNING `+seedLotColumns,
		l.Vendor, l.SourceURL, l.SKU, l.LotCode, l.PurchasedAt, l.PackedForYear,
		l.Quantity, l.Unit, l.CostCents, l.GerminationPct, l.Notes,
		l.ID, l.Version,
	))
	if errors.Is(err, sql.ErrNoRows) {
		current, gerr := d.GetSeedLot(ctx, l.ID)
		if gerr != nil {
			return nil, gerr
		}
		return current, domain.ErrVersionConflict
	}
	if err != nil {
		return nil, fmt.Errorf("store: update seed lot: %w", err)
	}
	return updated, nil
}

// DeleteSeedLot removes a lot. Plantings attributed to it survive with a NULL
// seed_lot_id (see the migration): the plants really were in the ground,
// whatever happened to the record of the packet.
func (d *DB) DeleteSeedLot(ctx context.Context, id int64) error {
	res, err := d.sql.ExecContext(ctx, `DELETE FROM seed_lots WHERE id = ?`, id)
	if err != nil {
		return fmt.Errorf("store: delete seed lot: %w", err)
	}
	n, err := res.RowsAffected()
	if err != nil {
		return fmt.Errorf("store: seed lot delete rows: %w", err)
	}
	if n == 0 {
		return domain.ErrNotFound
	}
	return nil
}

// SeedLotUse is one active planting attributed to a lot, carrying just enough to
// compute its effective plant count.
type SeedLotUse struct {
	LotID     int64
	RadiusCM  float64
	Count     *int
	SpacingCM float64
}

// SeedLotUsage returns the ACTIVE plantings attributed to any of the owner's
// lots — the "used" half of a lot's remaining quantity.
//
// It returns the raw ingredients rather than a SUM, because the effective count
// of a planting is its explicit count when it has one and the derived
// π·r²/spacing² formula otherwise. That formula lives in the service; reproducing
// it in SQL would guarantee the two drift apart.
func (d *DB) SeedLotUsage(ctx context.Context, ownerID int64) ([]SeedLotUse, error) {
	rows, err := d.sql.QueryContext(ctx,
		`SELECT pl.seed_lot_id, pl.radius_cm, pl.count, p.spacing_cm
		   FROM plantings pl
		   JOIN seed_lots sl ON sl.id = pl.seed_lot_id
		   JOIN plants p     ON p.id = pl.plant_id
		  WHERE sl.owner_id = ? AND pl.removed_at IS NULL`,
		ownerID)
	if err != nil {
		return nil, fmt.Errorf("store: seed lot usage: %w", err)
	}
	defer rows.Close()

	uses := []SeedLotUse{}
	for rows.Next() {
		var u SeedLotUse
		if err := rows.Scan(&u.LotID, &u.RadiusCM, &u.Count, &u.SpacingCM); err != nil {
			return nil, fmt.Errorf("store: scan seed lot usage: %w", err)
		}
		uses = append(uses, u)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("store: iterate seed lot usage: %w", err)
	}
	return uses, nil
}