package api

import (
	"net/http"

	"github.com/gin-gonic/gin"

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

// Bulk operations on a plantable object (#82): fill a region with one plant, and
// clear everything out of it.
//
// These were reachable only through the agent toolbox until now, which meant the
// most valuable bulk operation in a garden planner — and the one carrying the
// most carefully reasoned geometry in the codebase — did not exist at all on an
// instance with no model configured. They are thin adapters over the same
// service methods `internal/agent/tools.go` calls, so the permission checks and
// the one-change-set-per-operation guarantee come along unchanged.

// fillRect is an explicit rectangle in the object's local frame, the alternative
// to a compass name. A named type (not an inline anonymous struct) to match the
// rest of internal/api and so it can carry its own validity check.
type fillRect struct {
	MinX float64 `json:"minXCm"`
	MinY float64 `json:"minYCm"`
	MaxX float64 `json:"maxXCm"`
	MaxY float64 `json:"maxYCm"`
}

// degenerate reports whether the rect encloses no area. Such a rect (including
// the all-zeros an empty `"rect": {}` decodes to) would otherwise slip through
// and plant a single plop at the object's centre — a surprising result for what
// is really malformed input.
func (r fillRect) degenerate() bool {
	return r.MaxX <= r.MinX || r.MaxY <= r.MinY
}

// objectFillRequest is the body for POST /objects/:id/fill.
//
// A region is given EITHER by compass name ("ne", "south half", "all") or as an
// explicit rect in the object's local frame. The named form is what a person
// means and what the agent uses; the rect is for a future drag-a-box affordance.
// Exactly one must be supplied — accepting both and silently preferring one
// would make a client bug look like a geometry bug.
type objectFillRequest struct {
	PlantID int64     `json:"plantId" binding:"required"`
	Region  string    `json:"region"`
	Rect    *fillRect `json:"rect"`
	// SpacingOverrideCM plants tighter or looser than the plant's mature spacing
	// without editing the catalog entry.
	SpacingOverrideCM *float64 `json:"spacingOverrideCm"`
	// Layout is "clump" (default; fat clumps for a quick sketch) or "grid"
	// (individual plants in rows at true spacing). Empty = clump. An unknown value
	// is refused by the service (#77).
	Layout string `json:"layout"`
}

func (h *handlers) fillObject(c *gin.Context) {
	id, ok := parseIDParam(c, "id")
	if !ok {
		return
	}
	var req objectFillRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		writeAPIError(c, http.StatusBadRequest, "INVALID_INPUT", "a plantId and a region are required")
		return
	}
	named, hasRect := req.Region != "", req.Rect != nil
	if named == hasRect {
		writeAPIError(c, http.StatusBadRequest, "INVALID_INPUT",
			`supply exactly one of "region" (e.g. "all", "ne", "south half") or "rect"`)
		return
	}

	actor := mustActor(c).ID
	var (
		created []domain.Planting
		err     error
	)
	if rect := req.Rect; rect != nil {
		// Reject a zero-area rect here rather than let it plant one stray plop.
		// (Binding the pointer to `rect` also keeps the deref visibly guarded,
		// instead of reading req.Rect.MinX under an invariant from a line above.)
		if rect.degenerate() {
			writeAPIError(c, http.StatusBadRequest, "INVALID_INPUT", "rect must enclose a positive area")
			return
		}
		region := service.Region{MinX: rect.MinX, MinY: rect.MinY, MaxX: rect.MaxX, MaxY: rect.MaxY}
		created, err = h.svc.FillRegion(c.Request.Context(), actor, id, region, req.PlantID, req.SpacingOverrideCM, service.FillLayout(req.Layout))
	} else {
		created, err = h.svc.FillNamedRegion(c.Request.Context(), actor, id, req.Region, req.PlantID, req.SpacingOverrideCM, service.FillLayout(req.Layout))
	}
	if err != nil {
		writeServiceError(c, err)
		return
	}
	// 200, not 201: a fill can legitimately create nothing (the region is already
	// planted), and there is no single resource to point a Location at.
	c.JSON(http.StatusOK, gin.H{"plantings": created, "created": len(created)})
}

// clearObject soft-removes every active plop in an object.
//
// Distinct from deleting the object, and — unlike the client-side loop this
// replaces — it lands as ONE change set, so undoing a cleared bed is one click
// rather than one per plop.
func (h *handlers) clearObject(c *gin.Context) {
	id, ok := parseIDParam(c, "id")
	if !ok {
		return
	}
	n, err := h.svc.ClearObject(c.Request.Context(), mustActor(c).ID, id)
	if err != nil {
		writeServiceError(c, err)
		return
	}
	c.JSON(http.StatusOK, gin.H{"cleared": n})
}