package service

import (
	"context"
	"strings"

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

// Plant field bounds. Spacing is mature in-row spacing in cm; the ceiling is a
// generous sanity limit (also rejecting NaN/Inf). Name/notes are length-capped so
// untrusted input can't balloon storage; icon holds one emoji (possibly a
// multi-codepoint ZWJ sequence, hence a byte cap rather than length 1).
const (
	maxPlantNameLen   = 200
	maxPlantNotesLen  = 10_000
	maxPlantIconLen   = 32
	minPlantSpacingCM = 0.1
	maxPlantSpacingCM = 10_000 // 100 m — headroom for large trees/shrubs
	maxDaysToMaturity = 3650   // ~10 years
)

// plantCategories is the set of valid category enum values (mirrors the schema
// CHECK constraint in 0001_init.sql).
var plantCategories = map[string]struct{}{
	domain.CategoryVegetable: {},
	domain.CategoryHerb:      {},
	domain.CategoryFlower:    {},
	domain.CategoryFruit:     {},
	domain.CategoryTreeShrub: {},
	domain.CategoryCover:     {},
}

// PlantInput is the mutable field set for creating a plant. DaysToMaturity is
// optional (nil = unknown).
type PlantInput struct {
	Name           string
	Category       string
	SpacingCM      float64
	Color          string
	Icon           string
	DaysToMaturity *int
	Notes          string
}

// PlantPatch is a partial update: nil fields are left unchanged. DaysToMaturity
// is itself nullable, so SetDays distinguishes "clear to NULL" (SetDays=true,
// value nil) from "leave unchanged" (SetDays=false) — a plain nil can't.
type PlantPatch struct {
	Name           *string
	Category       *string
	SpacingCM      *float64
	Color          *string
	Icon           *string
	SetDays        bool
	DaysToMaturity *int
	Notes          *string
}

// ListPlants returns the plants the actor can see: built-ins plus their own.
func (s *Service) ListPlants(ctx context.Context, actorID int64) ([]domain.Plant, error) {
	return s.store.ListPlantsForActor(ctx, actorID)
}

// CreatePlant adds a plant owned by the actor. To "clone" a built-in the client
// simply POSTs a copy — there is no dedicated endpoint, and the copy is owned by
// (and editable by) the actor.
func (s *Service) CreatePlant(ctx context.Context, actorID int64, in PlantInput) (*domain.Plant, error) {
	p := &domain.Plant{
		Name:           strings.TrimSpace(in.Name),
		Category:       in.Category,
		SpacingCM:      in.SpacingCM,
		Color:          in.Color,
		Icon:           strings.TrimSpace(in.Icon),
		DaysToMaturity: in.DaysToMaturity,
		Notes:          strings.TrimSpace(in.Notes),
	}
	if err := finalizePlant(p); err != nil {
		return nil, err
	}
	owner := actorID
	p.OwnerID = &owner
	return s.store.CreatePlant(ctx, p)
}

// writablePlant loads a plant and enforces that the actor may modify it. It is
// THE authorization point for plant mutation. Built-in rows (owner_id nil) are
// visible to everyone but read-only → ErrForbidden. A row owned by someone else
// is invisible → ErrNotFound (masking existence, as gardens/objects do). Only the
// actor's own rows are writable.
func (s *Service) writablePlant(ctx context.Context, actorID, plantID int64) (*domain.Plant, error) {
	p, err := s.store.GetPlant(ctx, plantID)
	if err != nil {
		return nil, err // ErrNotFound
	}
	if p.OwnerID == nil {
		return nil, domain.ErrForbidden // built-in: seeded and read-only
	}
	if *p.OwnerID != actorID {
		return nil, domain.ErrNotFound // another user's plant: not visible
	}
	return p, nil
}

// UpdatePlant applies a partial, version-guarded patch to the actor's own plant.
// On a version mismatch it returns (current, ErrVersionConflict).
func (s *Service) UpdatePlant(ctx context.Context, actorID, plantID int64, patch PlantPatch, version int64) (*domain.Plant, error) {
	p, err := s.writablePlant(ctx, actorID, plantID)
	if err != nil {
		return nil, err
	}
	applyPlantPatch(p, patch)
	if err := finalizePlant(p); err != nil {
		return nil, err
	}
	p.Version = version
	return s.store.UpdatePlant(ctx, p)
}

// DeletePlant removes the actor's own plant. A plant still referenced by any
// planting (even a removed one — the FK is RESTRICT) is refused with
// ErrPlantInUse rather than orphaning history; the client clones-and-edits or
// clears the plantings first.
func (s *Service) DeletePlant(ctx context.Context, actorID, plantID int64) error {
	if _, err := s.writablePlant(ctx, actorID, plantID); err != nil {
		return err
	}
	n, err := s.store.CountPlantingsForPlant(ctx, plantID)
	if err != nil {
		return err
	}
	if n > 0 {
		return domain.ErrPlantInUse
	}
	return s.store.DeletePlant(ctx, plantID)
}

// applyPlantPatch mutates p with each provided (non-nil) patch field.
func applyPlantPatch(p *domain.Plant, patch PlantPatch) {
	if patch.Name != nil {
		p.Name = strings.TrimSpace(*patch.Name)
	}
	if patch.Category != nil {
		p.Category = *patch.Category
	}
	if patch.SpacingCM != nil {
		p.SpacingCM = *patch.SpacingCM
	}
	if patch.Color != nil {
		p.Color = *patch.Color
	}
	if patch.Icon != nil {
		p.Icon = strings.TrimSpace(*patch.Icon)
	}
	if patch.SetDays {
		p.DaysToMaturity = patch.DaysToMaturity
	}
	if patch.Notes != nil {
		p.Notes = strings.TrimSpace(*patch.Notes)
	}
}

// finalizePlant validates a built/merged plant. Shared by create and update so
// both enforce the same invariants. isFinite/isHexColor live in objects.go.
func finalizePlant(p *domain.Plant) error {
	if p.Name == "" || len(p.Name) > maxPlantNameLen {
		return domain.ErrInvalidInput
	}
	if _, ok := plantCategories[p.Category]; !ok {
		return domain.ErrInvalidInput
	}
	if !isFinite(p.SpacingCM) || p.SpacingCM < minPlantSpacingCM || p.SpacingCM > maxPlantSpacingCM {
		return domain.ErrInvalidInput
	}
	if !isHexColor(p.Color) {
		return domain.ErrInvalidInput
	}
	if p.Icon == "" || len(p.Icon) > maxPlantIconLen {
		return domain.ErrInvalidInput
	}
	if p.DaysToMaturity != nil && (*p.DaysToMaturity < 1 || *p.DaysToMaturity > maxDaysToMaturity) {
		return domain.ErrInvalidInput
	}
	if len(p.Notes) > maxPlantNotesLen {
		return domain.ErrInvalidInput
	}
	return nil
}