"use client";

import { useState } from "react";
import { useRouter } from "next/navigation";
import { Wand2, Loader2, X } from "lucide-react";
import { toast } from "sonner";
import { Button } from "@/components/ui/button";
import {
  Dialog,
  DialogContent,
  DialogHeader,
  DialogTitle,
  DialogDescription,
} from "@/components/ui/dialog";
import { Textarea } from "@/components/ui/textarea";
import { Label } from "@/components/ui/label";
import { cn } from "@/lib/utils";

type Ingredient = { rawName: string };

export function AdaptRecipeButton({
  recipeId,
  ingredients,
}: {
  recipeId: string;
  ingredients: Ingredient[];
}) {
  const router = useRouter();
  const [open, setOpen] = useState(false);
  const [excluded, setExcluded] = useState<Set<string>>(new Set());
  const [extraConstraints, setExtraConstraints] = useState("");
  const [adapting, setAdapting] = useState(false);
  const [adaptationNotes, setAdaptationNotes] = useState("");

  function toggleExclude(name: string) {
    setExcluded((prev) => {
      const next = new Set(prev);
      if (next.has(name)) next.delete(name);
      else next.add(name);
      return next;
    });
  }

  function reset() {
    setExcluded(new Set());
    setExtraConstraints("");
    setAdaptationNotes("");
  }

  async function handleAdapt() {
    if (excluded.size === 0 && !extraConstraints.trim()) {
      toast.error("Select at least one ingredient to exclude or add a constraint");
      return;
    }

    setAdapting(true);
    setAdaptationNotes("");
    try {
      const res = await fetch(`/api/v1/ai/adapt/${recipeId}`, {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({
          excludeIngredients: Array.from(excluded),
          extraConstraints: extraConstraints.trim() || undefined,
        }),
      });

      if (!res.ok) {
        const err = await res.json() as { error?: string };
        toast.error(err.error ?? "Failed to adapt recipe");
        return;
      }

      const { id, adaptationNotes: notes } = await res.json() as { id: string; adaptationNotes: string };
      setAdaptationNotes(notes);
      toast.success("Adapted recipe saved as draft");
      setOpen(false);
      reset();
      router.push(`/recipes/${id}/edit`);
    } finally {
      setAdapting(false);
    }
  }

  const hasConstraints = excluded.size > 0 || extraConstraints.trim().length > 0;

  return (
    <>
      <Button variant="outline" size="sm" onClick={() => setOpen(true)}>
        <Wand2 className="h-4 w-4" />
        Adapt
      </Button>

      <Dialog open={open} onOpenChange={(v) => { setOpen(v); if (!v) reset(); }}>
        <DialogContent className="max-w-2xl">
          <DialogHeader>
            <DialogTitle className="flex items-center gap-2">
              <Wand2 className="h-5 w-5 text-primary" />
              Adapt this recipe
            </DialogTitle>
            <DialogDescription>
              Tap ingredients to exclude them. AI will find the best substitutes while preserving the dish.
            </DialogDescription>
          </DialogHeader>

          <div className="space-y-5">
            {/* Ingredient chips */}
            <div className="space-y-2">
              <Label>
                Exclude ingredients
                {excluded.size > 0 && (
                  <span className="ml-2 text-xs text-destructive font-normal">
                    {excluded.size} excluded
                  </span>
                )}
              </Label>
              <div className="flex flex-wrap gap-2">
                {ingredients.map((ing, idx) => {
                  const isExcluded = excluded.has(ing.rawName);
                  return (
                    <button
                      key={`${ing.rawName}-${idx}`}
                      type="button"
                      onClick={() => toggleExclude(ing.rawName)}
                      className={cn(
                        "inline-flex items-center gap-1.5 px-3 py-1.5 rounded-full text-sm border transition-all",
                        isExcluded
                          ? "bg-destructive/10 border-destructive/40 text-destructive line-through"
                          : "bg-muted border-transparent hover:border-border hover:bg-accent"
                      )}
                    >
                      {isExcluded && <X className="h-3 w-3 shrink-0" />}
                      {ing.rawName}
                    </button>
                  );
                })}
              </div>
            </div>

            {/* Free-text constraints */}
            <div className="space-y-2">
              <Label htmlFor="extra-constraints">
                Additional constraints
                <span className="ml-2 text-xs text-muted-foreground font-normal">optional</span>
              </Label>
              <Textarea
                id="extra-constraints"
                value={extraConstraints}
                onChange={(e) => setExtraConstraints(e.target.value)}
                placeholder="e.g. Make it vegan, lower the calories, use pantry staples only, gluten-free…"
                rows={2}
                disabled={adapting}
              />
            </div>

            {adapting && (
              <p className="text-sm text-muted-foreground">
                Adapting recipe — this may take 20–30 seconds…
              </p>
            )}

            <div className="flex gap-2 justify-end">
              <Button
                variant="outline"
                onClick={() => { setOpen(false); reset(); }}
                disabled={adapting}
              >
                Cancel
              </Button>
              {excluded.size > 0 && (
                <Button variant="ghost" size="sm" onClick={() => setExcluded(new Set())} disabled={adapting}>
                  Clear
                </Button>
              )}
              <Button onClick={handleAdapt} disabled={adapting || !hasConstraints}>
                {adapting
                  ? <><Loader2 className="h-4 w-4 animate-spin" />Adapting…</>
                  : <><Wand2 className="h-4 w-4" />Adapt recipe</>
                }
              </Button>
            </div>
          </div>
        </DialogContent>
      </Dialog>
    </>
  );
}