package store

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

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

// plantColumns lists plants columns in the order scanPlant expects.
const plantColumns = `id, owner_id, name, category, spacing_cm, color, icon,
	days_to_maturity, notes, version, created_at, updated_at`

func scanPlant(s scanner) (*domain.Plant, error) {
	var p domain.Plant
	if err := s.Scan(
		&p.ID, &p.OwnerID, &p.Name, &p.Category, &p.SpacingCM, &p.Color, &p.Icon,
		&p.DaysToMaturity, &p.Notes, &p.Version, &p.CreatedAt, &p.UpdatedAt,
	); err != nil {
		return nil, err
	}
	return &p, nil
}

// ListReferencedPlants returns the distinct plants used by a garden's active
// plantings — the catalog subset the editor needs to render them. Always a
// non-nil slice (empty until plantings exist, #14). Full plant CRUD/seeding is
// #12; this is only the /full read side.
func (d *DB) ListReferencedPlants(ctx context.Context, gardenID int64) ([]domain.Plant, error) {
	rows, err := d.sql.QueryContext(ctx,
		`SELECT DISTINCT `+qualifyColumns("p", plantColumns)+` FROM plants p
		   JOIN plantings pl ON pl.plant_id = p.id
		   JOIN garden_objects o ON o.id = pl.object_id
		  WHERE o.garden_id = ? AND pl.removed_at IS NULL
		  ORDER BY p.id`,
		gardenID,
	)
	if err != nil {
		return nil, fmt.Errorf("store: list referenced plants: %w", err)
	}
	defer rows.Close()

	plants := []domain.Plant{}
	for rows.Next() {
		p, err := scanPlant(rows)
		if err != nil {
			return nil, fmt.Errorf("store: scan plant: %w", err)
		}
		plants = append(plants, *p)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("store: iterate plants: %w", err)
	}
	return plants, nil
}

// maxPlantsListed caps ListPlantsForActor as a defensive backstop. The seeded
// built-ins (~30) plus a user's own catalog stay tiny at household scale, so this
// is never hit; pagination is post-v1 if ever needed.
const maxPlantsListed = 5000

// ListPlantsForActor returns the plants a user can see: every built-in
// (owner_id NULL) plus the user's own rows, built-ins first then by name. Always
// a non-nil slice. This is the catalog list; ListReferencedPlants above is the
// narrower /full read.
func (d *DB) ListPlantsForActor(ctx context.Context, actorID int64) ([]domain.Plant, error) {
	rows, err := d.sql.QueryContext(ctx,
		`SELECT `+plantColumns+` FROM plants
		  WHERE owner_id IS NULL OR owner_id = ?
		  ORDER BY owner_id IS NOT NULL, name COLLATE NOCASE, id
		  LIMIT ?`,
		actorID, maxPlantsListed,
	)
	if err != nil {
		return nil, fmt.Errorf("store: list plants: %w", err)
	}
	defer rows.Close()

	plants := []domain.Plant{}
	for rows.Next() {
		p, err := scanPlant(rows)
		if err != nil {
			return nil, fmt.Errorf("store: scan plant: %w", err)
		}
		plants = append(plants, *p)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("store: iterate plants: %w", err)
	}
	return plants, nil
}

// GetPlant returns the plant with the given id, or domain.ErrNotFound. Visibility
// (built-in vs owned) is the service layer's call, not this raw read's.
func (d *DB) GetPlant(ctx context.Context, id int64) (*domain.Plant, error) {
	p, err := scanPlant(d.sql.QueryRowContext(ctx,
		`SELECT `+plantColumns+` FROM plants WHERE id = ?`, id))
	if errors.Is(err, sql.ErrNoRows) {
		return nil, domain.ErrNotFound
	}
	if err != nil {
		return nil, fmt.Errorf("store: get plant: %w", err)
	}
	return p, nil
}

// CreatePlant inserts a plant (fields already validated by the service) and
// returns the stored row. OwnerID is the creating user — built-ins are seeded by
// migration only, never through this path.
func (d *DB) CreatePlant(ctx context.Context, p *domain.Plant) (*domain.Plant, error) {
	created, err := scanPlant(d.sql.QueryRowContext(ctx,
		`INSERT INTO plants (owner_id, name, category, spacing_cm, color, icon, days_to_maturity, notes)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?)
		 RETURNING `+plantColumns,
		p.OwnerID, p.Name, p.Category, p.SpacingCM, p.Color, p.Icon, p.DaysToMaturity, p.Notes,
	))
	if err != nil {
		return nil, fmt.Errorf("store: insert plant: %w", err)
	}
	return created, nil
}

// UpdatePlant applies a version-guarded update of all mutable columns (the
// service merges partial patches first). Returns the updated row, or
// (current row, ErrVersionConflict) / ErrNotFound — the same contract as
// UpdateGarden/UpdateObject.
func (d *DB) UpdatePlant(ctx context.Context, p *domain.Plant) (*domain.Plant, error) {
	updated, err := scanPlant(d.sql.QueryRowContext(ctx,
		`UPDATE plants
		    SET name = ?, category = ?, spacing_cm = ?, color = ?, icon = ?,
		        days_to_maturity = ?, notes = ?,
		        version = version + 1,
		        updated_at = strftime('%Y-%m-%dT%H:%M:%SZ', 'now')
		  WHERE id = ? AND version = ?
		  RETURNING `+plantColumns,
		p.Name, p.Category, p.SpacingCM, p.Color, p.Icon, p.DaysToMaturity, p.Notes,
		p.ID, p.Version,
	))
	if errors.Is(err, sql.ErrNoRows) {
		current, gerr := d.GetPlant(ctx, p.ID)
		if gerr != nil {
			return nil, gerr
		}
		return current, domain.ErrVersionConflict
	}
	if err != nil {
		return nil, fmt.Errorf("store: update plant: %w", err)
	}
	return updated, nil
}

// CountPlantingsForPlant returns how many plantings reference a plant, INCLUDING
// removed ones — a removed_at row still holds the FK (ON DELETE RESTRICT), so any
// row blocks deletion. The service checks this to refuse a delete with a clear
// error before the constraint fires.
func (d *DB) CountPlantingsForPlant(ctx context.Context, plantID int64) (int, error) {
	var n int
	if err := d.sql.QueryRowContext(ctx,
		`SELECT count(*) FROM plantings WHERE plant_id = ?`, plantID).Scan(&n); err != nil {
		return 0, fmt.Errorf("store: count plantings for plant: %w", err)
	}
	return n, nil
}

// DeletePlant removes a plant. Returns domain.ErrNotFound if no row was deleted,
// or domain.ErrPlantInUse if the ON DELETE RESTRICT foreign key from plantings
// fires (a backstop for the service's own count check under a concurrent insert).
func (d *DB) DeletePlant(ctx context.Context, id int64) error {
	res, err := d.sql.ExecContext(ctx, `DELETE FROM plants WHERE id = ?`, id)
	if err != nil {
		if isForeignKeyViolation(err) {
			return domain.ErrPlantInUse
		}
		return fmt.Errorf("store: delete plant: %w", err)
	}
	n, err := res.RowsAffected()
	if err != nil {
		return fmt.Errorf("store: plant delete rows: %w", err)
	}
	if n == 0 {
		return domain.ErrNotFound
	}
	return nil
}