package service

import (
	"context"
	"encoding/json"
	"math"
	"strings"

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

const (
	maxObjectNameLen  = 200
	maxObjectNotesLen = 10_000
	maxObjectPropsLen = 20_000
)

// objectKinds maps each valid garden_objects.kind to its traits. plantable is
// the default (beds/bags/containers/in-ground hold plants; trees/paths/
// structures don't) and is overridable per object.
var objectKinds = map[string]struct{ plantable bool }{
	domain.KindBed:       {plantable: true},
	domain.KindGrowBag:   {plantable: true},
	domain.KindContainer: {plantable: true},
	domain.KindInGround:  {plantable: true},
	domain.KindTree:      {plantable: false},
	domain.KindPath:      {plantable: false},
	domain.KindStructure: {plantable: false},
}

// ObjectInput is the payload for creating a garden object. Plantable nil means
// "default for this kind".
type ObjectInput struct {
	Kind        string
	Name        string
	Shape       string
	XCM         float64
	YCM         float64
	WidthCM     float64
	HeightCM    float64
	RotationDeg float64
	ZIndex      int
	Plantable   *bool
	Color       *string
	Props       *string
	Notes       string
}

// ObjectPatch is a partial update: every field is optional (nil = leave as-is).
// Kind and shape are intentionally immutable after creation.
//
// Color and Props are nullable in the DB, so they use an explicit "set" flag to
// tell "clear to NULL" (Set*=true, value nil) apart from "leave unchanged"
// (Set*=false) — a plain nil pointer can't express both.
type ObjectPatch struct {
	Name        *string
	XCM         *float64
	YCM         *float64
	WidthCM     *float64
	HeightCM    *float64
	RotationDeg *float64
	ZIndex      *int
	Plantable   *bool
	SetColor    bool
	Color       *string
	SetProps    bool
	Props       *string
	Notes       *string
}

// FullGarden is the one-shot editor payload: the garden plus everything drawn in
// it — objects, active plantings (each with its DerivedCount filled in), and the
// plants those plantings reference.
type FullGarden struct {
	Garden    *domain.Garden        `json:"garden"`
	Objects   []domain.GardenObject `json:"objects"`
	Plantings []domain.Planting     `json:"plantings"`
	Plants    []domain.Plant        `json:"plants"`
}

// CreateObject adds an object to a garden the actor can edit.
func (s *Service) CreateObject(ctx context.Context, actorID, gardenID int64, in ObjectInput) (*domain.GardenObject, error) {
	g, err := s.requireGardenRole(ctx, actorID, gardenID, roleEditor)
	if err != nil {
		return nil, err
	}

	// finalizeObject is the single validation point (it rejects an unknown kind),
	// so an unknown kind here just yields plantable=false before being rejected.
	shape := in.Shape
	if shape == "" {
		shape = domain.ShapeRect
	}
	plantable := objectKinds[in.Kind].plantable
	if in.Plantable != nil {
		plantable = *in.Plantable
	}

	o := &domain.GardenObject{
		GardenID:    gardenID,
		Kind:        in.Kind,
		Name:        strings.TrimSpace(in.Name),
		Shape:       shape,
		XCM:         in.XCM,
		YCM:         in.YCM,
		WidthCM:     in.WidthCM,
		HeightCM:    in.HeightCM,
		RotationDeg: in.RotationDeg,
		ZIndex:      in.ZIndex,
		Plantable:   plantable,
		Color:       in.Color,
		Props:       in.Props,
		Notes:       strings.TrimSpace(in.Notes),
	}
	if err := finalizeObject(o, g); err != nil {
		return nil, err
	}
	return s.store.CreateObject(ctx, o)
}

// objectForRole loads an object and enforces that the actor holds at least min
// on its owning garden, returning both. A missing object — or one in a garden
// the actor can't see — is ErrNotFound (existence masked, same as gardens).
func (s *Service) objectForRole(ctx context.Context, actorID, objectID int64, min gardenRole) (*domain.GardenObject, *domain.Garden, error) {
	o, err := s.store.GetObject(ctx, objectID)
	if err != nil {
		return nil, nil, err // ErrNotFound
	}
	g, err := s.requireGardenRole(ctx, actorID, o.GardenID, min)
	if err != nil {
		return nil, nil, err
	}
	return o, g, nil
}

// UpdateObject applies a partial, version-guarded patch to an object in a garden
// the actor can edit. On a version mismatch it returns (current, ErrVersionConflict).
func (s *Service) UpdateObject(ctx context.Context, actorID, objectID int64, patch ObjectPatch, version int64) (*domain.GardenObject, error) {
	o, g, err := s.objectForRole(ctx, actorID, objectID, roleEditor)
	if err != nil {
		return nil, err
	}

	applyObjectPatch(o, patch)
	if err := finalizeObject(o, g); err != nil {
		return nil, err
	}
	o.Version = version
	return s.store.UpdateObject(ctx, o)
}

// DeleteObject removes an object (its plantings cascade) from a garden the actor
// can edit.
func (s *Service) DeleteObject(ctx context.Context, actorID, objectID int64) error {
	if _, _, err := s.objectForRole(ctx, actorID, objectID, roleEditor); err != nil {
		return err
	}
	return s.store.DeleteObject(ctx, objectID)
}

// GardenFull returns the whole editor payload for a garden the actor can view.
func (s *Service) GardenFull(ctx context.Context, actorID, gardenID int64) (*FullGarden, error) {
	g, err := s.requireGardenRole(ctx, actorID, gardenID, roleViewer)
	if err != nil {
		return nil, err
	}
	return s.assembleFull(ctx, g)
}

// assembleFull builds the read-only /full payload for an already-authorized
// garden: its objects, active plops (with DerivedCount filled in), and the
// plants those plops reference. Shared by the authenticated GardenFull and the
// unauthenticated PublicGarden read, so both return the identical shape.
func (s *Service) assembleFull(ctx context.Context, g *domain.Garden) (*FullGarden, error) {
	objects, err := s.store.ListObjectsForGarden(ctx, g.ID)
	if err != nil {
		return nil, err
	}
	plantings, err := s.store.ListActivePlantingsForGarden(ctx, g.ID)
	if err != nil {
		return nil, err
	}
	plants, err := s.store.ListReferencedPlants(ctx, g.ID)
	if err != nil {
		return nil, err
	}
	// Fill each plop's DerivedCount from its plant's spacing (referenced plants
	// are already loaded, so this is a map lookup rather than N queries).
	spacing := make(map[int64]float64, len(plants))
	for _, pl := range plants {
		spacing[pl.ID] = pl.SpacingCM
	}
	for i := range plantings {
		plantings[i].DerivedCount = derivedCount(plantings[i].RadiusCM, spacing[plantings[i].PlantID])
	}
	return &FullGarden{Garden: g, Objects: objects, Plantings: plantings, Plants: plants}, nil
}

// applyObjectPatch mutates o with each provided (non-nil) patch field.
func applyObjectPatch(o *domain.GardenObject, p ObjectPatch) {
	if p.Name != nil {
		o.Name = strings.TrimSpace(*p.Name)
	}
	if p.XCM != nil {
		o.XCM = *p.XCM
	}
	if p.YCM != nil {
		o.YCM = *p.YCM
	}
	if p.WidthCM != nil {
		o.WidthCM = *p.WidthCM
	}
	if p.HeightCM != nil {
		o.HeightCM = *p.HeightCM
	}
	if p.RotationDeg != nil {
		o.RotationDeg = *p.RotationDeg
	}
	if p.ZIndex != nil {
		o.ZIndex = *p.ZIndex
	}
	if p.Plantable != nil {
		o.Plantable = *p.Plantable
	}
	// Color/Props: Set* distinguishes "clear to NULL" (value nil) from unchanged.
	if p.SetColor {
		o.Color = p.Color
	}
	if p.SetProps {
		o.Props = p.Props
	}
	if p.Notes != nil {
		o.Notes = strings.TrimSpace(*p.Notes)
	}
}

// finalizeObject normalizes (rotation → [0,360)) and validates a built/merged
// object against its garden. Shared by create and update so both enforce the
// same invariants.
func finalizeObject(o *domain.GardenObject, g *domain.Garden) error {
	if _, ok := objectKinds[o.Kind]; !ok {
		return domain.ErrInvalidInput
	}
	// rect/circle only; polygon is reserved in the schema but not supported yet.
	if o.Shape != domain.ShapeRect && o.Shape != domain.ShapeCircle {
		return domain.ErrInvalidInput
	}
	if len(o.Name) > maxObjectNameLen || len(o.Notes) > maxObjectNotesLen {
		return domain.ErrInvalidInput
	}
	if !validDimensionCM(o.WidthCM) || !validDimensionCM(o.HeightCM) {
		return domain.ErrInvalidInput
	}
	if !isFinite(o.XCM) || !isFinite(o.YCM) || !isFinite(o.RotationDeg) {
		return domain.ErrInvalidInput
	}
	o.RotationDeg = normalizeDegrees(o.RotationDeg)

	// Loose placement check: the (unrotated) bounding box must overlap the garden
	// at all — partial overhang is fine, fully off-field is not.
	if !bboxOverlapsGarden(o, g) {
		return domain.ErrInvalidInput
	}

	if o.Color != nil && !isHexColor(*o.Color) {
		return domain.ErrInvalidInput
	}
	if o.Props != nil {
		if len(*o.Props) > maxObjectPropsLen || !json.Valid([]byte(*o.Props)) {
			return domain.ErrInvalidInput
		}
	}
	return nil
}

func isFinite(v float64) bool { return !math.IsNaN(v) && !math.IsInf(v, 0) }

// normalizeDegrees folds an angle into [0, 360).
func normalizeDegrees(d float64) float64 {
	d = math.Mod(d, 360)
	if d < 0 {
		d += 360
	}
	return d
}

// bboxOverlapsGarden reports whether the object's axis-aligned (unrotated)
// bounding box intersects the garden rectangle [0,width]×[0,height].
func bboxOverlapsGarden(o *domain.GardenObject, g *domain.Garden) bool {
	halfW, halfH := o.WidthCM/2, o.HeightCM/2
	left, right := o.XCM-halfW, o.XCM+halfW
	top, bottom := o.YCM-halfH, o.YCM+halfH
	return left < g.WidthCM && right > 0 && top < g.HeightCM && bottom > 0
}

// isHexColor accepts #rgb or #rrggbb (case-insensitive).
func isHexColor(s string) bool {
	if len(s) != 4 && len(s) != 7 {
		return false
	}
	if s[0] != '#' {
		return false
	}
	for _, c := range s[1:] {
		if !((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')) {
			return false
		}
	}
	return true
}