"use client";

import { useState, useEffect, useRef } from "react";
import { z } from "zod";
import { Trash2, Plus, ChevronDown, ChevronUp } from "lucide-react";
import { Sheet, SheetContent, SheetHeader, SheetTitle } from "@/components/ui/sheet";
import { Button } from "@/components/ui/button";
import { TagInput } from "./tag-input";
import { BlockTimeline, BLOCK_COLORS, timeToMins, minsToTime } from "./block-timeline";
import { SeriesPicker } from "./series-picker";
import { FilterPreview } from "./filter-preview";
import { useCollections, useSeries, useGenres } from "@/hooks/use-library";
import type {
  ChannelResponse,
  ProgrammingBlock,
  BlockContent,
  FillStrategy,
  ContentType,
  MediaFilter,
  RecyclePolicy,
} from "@/lib/types";

// ---------------------------------------------------------------------------
// Zod schemas
// ---------------------------------------------------------------------------

const mediaFilterSchema = z.object({
  content_type: z.enum(["movie", "episode", "short"]).nullable().optional(),
  genres: z.array(z.string()),
  decade: z
    .number()
    .int()
    .min(1900, "Decade must be ≥ 1900")
    .max(2099, "Decade must be ≤ 2090")
    .nullable()
    .optional(),
  tags: z.array(z.string()),
  min_duration_secs: z.number().min(0, "Must be ≥ 0").nullable().optional(),
  max_duration_secs: z.number().min(0, "Must be ≥ 0").nullable().optional(),
  collections: z.array(z.string()),
  series_names: z.array(z.string()),
  search_term: z.string().nullable().optional(),
});

const blockSchema = z.object({
  id: z.string(),
  name: z.string().min(1, "Block name is required"),
  start_time: z.string(),
  duration_mins: z.number().int().min(1, "Must be at least 1 minute"),
  content: z.discriminatedUnion("type", [
    z.object({
      type: z.literal("algorithmic"),
      filter: mediaFilterSchema,
      strategy: z.enum(["best_fit", "sequential", "random"]),
    }),
    z.object({
      type: z.literal("manual"),
      items: z.array(z.string()),
    }),
  ]),
  loop_on_finish: z.boolean().optional(),
  ignore_recycle_policy: z.boolean().optional(),
});

const channelFormSchema = z.object({
  name: z.string().min(1, "Name is required"),
  timezone: z.string().min(1, "Timezone is required"),
  description: z.string().optional(),
  blocks: z.array(blockSchema),
  recycle_policy: z.object({
    cooldown_days: z.number().int().min(0).nullable().optional(),
    cooldown_generations: z.number().int().min(0).nullable().optional(),
    min_available_ratio: z.number().min(0, "Must be ≥ 0").max(1, "Must be ≤ 1"),
  }),
});

type FieldErrors = Record<string, string | undefined>;

function extractErrors(err: z.ZodError): FieldErrors {
  const map: FieldErrors = {};
  for (const issue of err.issues) {
    const key = issue.path.join(".");
    if (!map[key]) map[key] = issue.message;
  }
  return map;
}

// ---------------------------------------------------------------------------
// Field wrapper
// ---------------------------------------------------------------------------

function Field({
  label,
  hint,
  error,
  children,
}: {
  label: string;
  hint?: string;
  error?: string;
  children: React.ReactNode;
}) {
  return (
    <div className="space-y-1.5">
      <label className="block text-xs font-medium text-zinc-400">{label}</label>
      {children}
      {error ? (
        <p className="text-[11px] text-red-400">{error}</p>
      ) : hint ? (
        <p className="text-[11px] text-zinc-600">{hint}</p>
      ) : null}
    </div>
  );
}

function TextInput({
  value,
  onChange,
  placeholder,
  required,
  error,
}: {
  value: string;
  onChange: (v: string) => void;
  placeholder?: string;
  required?: boolean;
  error?: boolean;
}) {
  return (
    <input
      required={required}
      value={value}
      onChange={(e) => onChange(e.target.value)}
      placeholder={placeholder}
      className={`w-full rounded-md border bg-zinc-800 px-3 py-2 text-sm text-zinc-100 placeholder:text-zinc-600 focus:outline-none ${error ? "border-red-500 focus:border-red-400" : "border-zinc-700 focus:border-zinc-500"}`}
    />
  );
}

function NumberInput({
  value,
  onChange,
  min,
  max,
  step,
  placeholder,
  error,
}: {
  value: number | "";
  onChange: (v: number | "") => void;
  min?: number;
  max?: number;
  step?: number | "any";
  placeholder?: string;
  error?: boolean;
}) {
  return (
    <input
      type="number"
      min={min}
      max={max}
      step={step}
      value={value}
      placeholder={placeholder}
      onChange={(e) => onChange(e.target.value === "" ? "" : Number(e.target.value))}
      className={`w-full rounded-md border bg-zinc-800 px-3 py-2 text-sm text-zinc-100 placeholder:text-zinc-600 focus:outline-none ${error ? "border-red-500 focus:border-red-400" : "border-zinc-700 focus:border-zinc-500"}`}
    />
  );
}

function NativeSelect({
  value,
  onChange,
  children,
}: {
  value: string;
  onChange: (v: string) => void;
  children: React.ReactNode;
}) {
  return (
    <select
      value={value}
      onChange={(e) => onChange(e.target.value)}
      className="w-full rounded-md border border-zinc-700 bg-zinc-800 px-3 py-2 text-sm text-zinc-100 focus:border-zinc-500 focus:outline-none"
    >
      {children}
    </select>
  );
}

// ---------------------------------------------------------------------------
// Defaults
// ---------------------------------------------------------------------------

function defaultFilter(): MediaFilter {
  return {
    content_type: null,
    genres: [],
    decade: null,
    tags: [],
    min_duration_secs: null,
    max_duration_secs: null,
    collections: [],
    series_names: [],
    search_term: null,
  };
}

function defaultBlock(startMins = 20 * 60, durationMins = 60): ProgrammingBlock {
  return {
    id: crypto.randomUUID(),
    name: "",
    start_time: minsToTime(startMins),
    duration_mins: durationMins,
    content: { type: "algorithmic", filter: defaultFilter(), strategy: "random" },
    loop_on_finish: true,
    ignore_recycle_policy: false,
  };
}

// ---------------------------------------------------------------------------
// AlgorithmicFilterEditor — filter section with live library data
// ---------------------------------------------------------------------------

interface AlgorithmicFilterEditorProps {
  content: Extract<BlockContent, { type: "algorithmic" }>;
  pfx: string;
  errors: FieldErrors;
  setFilter: (patch: Partial<MediaFilter>) => void;
  setStrategy: (strategy: FillStrategy) => void;
}

function AlgorithmicFilterEditor({
  content,
  pfx,
  errors,
  setFilter,
  setStrategy,
}: AlgorithmicFilterEditorProps) {
  const [showGenres, setShowGenres] = useState(false);

  const { data: collections, isLoading: loadingCollections } = useCollections();
  const { data: series, isLoading: loadingSeries } = useSeries();
  const { data: genreOptions } = useGenres(content.filter.content_type ?? undefined);

  const isEpisode = content.filter.content_type === "episode";

  return (
    <div className="space-y-3 rounded-md border border-zinc-700/50 bg-zinc-800 p-3">
      <p className="text-[11px] font-medium uppercase tracking-wider text-zinc-500">Filter</p>

      <div className="grid grid-cols-2 gap-3">
        <Field label="Media type">
          <NativeSelect
            value={content.filter.content_type ?? ""}
            onChange={(v) =>
              setFilter({
                content_type: v === "" ? null : (v as ContentType),
                // clear series names if switching away from episode
                series_names: v !== "episode" ? [] : content.filter.series_names,
              })
            }
          >
            <option value="">Any</option>
            <option value="movie">Movie</option>
            <option value="episode">Episode</option>
            <option value="short">Short</option>
          </NativeSelect>
        </Field>
        <Field label="Strategy">
          <NativeSelect
            value={content.strategy}
            onChange={(v) => setStrategy(v as FillStrategy)}
          >
            <option value="random">Random</option>
            <option value="best_fit">Best fit</option>
            <option value="sequential">Sequential</option>
          </NativeSelect>
        </Field>
      </div>

      {/* Series — only meaningful for episodes */}
      {isEpisode && (
        <Field
          label="Series"
          hint={
            content.strategy === "sequential"
              ? "Episodes will play in chronological order"
              : "Filter to specific shows, or leave empty for all"
          }
        >
          <SeriesPicker
            values={content.filter.series_names ?? []}
            onChange={(v) => setFilter({ series_names: v })}
            series={series ?? []}
            isLoading={loadingSeries}
          />
        </Field>
      )}

      {/* Library — real collection names when the provider supports it */}
      <Field
        label="Library"
        hint={
          loadingCollections
            ? "Loading libraries…"
            : collections
              ? "Scope this block to one library"
              : "Enter a provider library ID"
        }
      >
        {collections && collections.length > 0 ? (
          <NativeSelect
            value={content.filter.collections[0] ?? ""}
            onChange={(v) => setFilter({ collections: v ? [v] : [] })}
          >
            <option value="">All libraries</option>
            {collections.map((c) => (
              <option key={c.id} value={c.id}>
                {c.name}
                {c.collection_type ? ` (${c.collection_type})` : ""}
              </option>
            ))}
          </NativeSelect>
        ) : (
          <TagInput
            values={content.filter.collections}
            onChange={(v) => setFilter({ collections: v })}
            placeholder="Library ID…"
          />
        )}
      </Field>

      {/* Genres with browse-from-library shortcut */}
      <Field label="Genres" hint="Press Enter or comma to add">
        <TagInput
          values={content.filter.genres}
          onChange={(v) => setFilter({ genres: v })}
          placeholder="Comedy, Animation…"
        />
        {genreOptions && genreOptions.length > 0 && (
          <div className="mt-1.5">
            <button
              type="button"
              onClick={() => setShowGenres((s) => !s)}
              className="text-[11px] text-zinc-600 hover:text-zinc-400"
            >
              {showGenres ? "Hide" : "Browse"} available genres
            </button>
            {showGenres && (
              <div className="mt-1.5 flex flex-wrap gap-1">
                {genreOptions
                  .filter((g) => !content.filter.genres.includes(g))
                  .map((g) => (
                    <button
                      key={g}
                      type="button"
                      onClick={() => setFilter({ genres: [...content.filter.genres, g] })}
                      className="rounded px-1.5 py-0.5 text-[11px] bg-zinc-700/50 text-zinc-400 hover:bg-zinc-700 hover:text-zinc-200"
                    >
                      + {g}
                    </button>
                  ))}
              </div>
            )}
          </div>
        )}
      </Field>

      <Field label="Tags" hint="Press Enter or comma to add">
        <TagInput
          values={content.filter.tags}
          onChange={(v) => setFilter({ tags: v })}
          placeholder="classic, family…"
        />
      </Field>

      <div className="grid grid-cols-3 gap-3">
        <Field label="Decade" hint="e.g. 1990" error={errors[`${pfx}.content.filter.decade`]}>
          <NumberInput
            value={content.filter.decade ?? ""}
            onChange={(v) => setFilter({ decade: v === "" ? null : (v as number) })}
            placeholder="1990"
            error={!!errors[`${pfx}.content.filter.decade`]}
          />
        </Field>
        <Field label="Min duration (s)" error={errors[`${pfx}.content.filter.min_duration_secs`]}>
          <NumberInput
            value={content.filter.min_duration_secs ?? ""}
            onChange={(v) =>
              setFilter({ min_duration_secs: v === "" ? null : (v as number) })
            }
            placeholder="1200"
            error={!!errors[`${pfx}.content.filter.min_duration_secs`]}
          />
        </Field>
        <Field label="Max duration (s)" error={errors[`${pfx}.content.filter.max_duration_secs`]}>
          <NumberInput
            value={content.filter.max_duration_secs ?? ""}
            onChange={(v) =>
              setFilter({ max_duration_secs: v === "" ? null : (v as number) })
            }
            placeholder="3600"
            error={!!errors[`${pfx}.content.filter.max_duration_secs`]}
          />
        </Field>
      </div>

      {/* Preview — snapshot of current filter+strategy, only fetches on explicit click */}
      <FilterPreview filter={content.filter} strategy={content.strategy} />
    </div>
  );
}

// ---------------------------------------------------------------------------
// BlockEditor (detail form for a single block)
// ---------------------------------------------------------------------------

interface BlockEditorProps {
  block: ProgrammingBlock;
  index: number;
  isSelected: boolean;
  color: string;
  errors: FieldErrors;
  onChange: (block: ProgrammingBlock) => void;
  onRemove: () => void;
  onSelect: () => void;
}

function BlockEditor({ block, index, isSelected, color, errors, onChange, onRemove, onSelect }: BlockEditorProps) {
  const [expanded, setExpanded] = useState(isSelected);
  const elRef = useRef<HTMLDivElement>(null);

  // Scroll into view when selected
  useEffect(() => {
    if (isSelected) {
      setExpanded(true);
      elRef.current?.scrollIntoView({ behavior: "smooth", block: "nearest" });
    }
  }, [isSelected]);

  const setField = <K extends keyof ProgrammingBlock>(key: K, value: ProgrammingBlock[K]) =>
    onChange({ ...block, [key]: value });

  const content = block.content;
  const pfx = `blocks.${index}`;

  const setContentType = (type: "algorithmic" | "manual") => {
    onChange({
      ...block,
      content:
        type === "algorithmic"
          ? { type: "algorithmic", filter: defaultFilter(), strategy: "random" }
          : { type: "manual", items: [] },
    });
  };

  const setFilter = (patch: Partial<MediaFilter>) => {
    if (content.type !== "algorithmic") return;
    onChange({ ...block, content: { ...content, filter: { ...content.filter, ...patch } } });
  };

  const setStrategy = (strategy: FillStrategy) => {
    if (content.type !== "algorithmic") return;
    onChange({ ...block, content: { ...content, strategy } });
  };

  return (
    <div
      ref={elRef}
      className={`rounded-lg border bg-zinc-800/50 ${isSelected ? "border-zinc-500" : "border-zinc-700"}`}
    >
      <div className="flex items-center gap-2 px-3 py-2">
        <div className="h-2.5 w-2.5 rounded-full shrink-0" style={{ backgroundColor: color }} />
        <button
          type="button"
          onClick={() => { setExpanded((v) => !v); onSelect(); }}
          className="flex flex-1 items-center gap-2 text-left text-sm font-medium text-zinc-200"
        >
          {expanded ? (
            <ChevronUp className="size-3.5 shrink-0 text-zinc-500" />
          ) : (
            <ChevronDown className="size-3.5 shrink-0 text-zinc-500" />
          )}
          <span className="truncate">{block.name || "Unnamed block"}</span>
          <span className="shrink-0 font-mono text-[11px] text-zinc-500">
            {block.start_time.slice(0, 5)} · {block.duration_mins}m
          </span>
        </button>
        <button
          type="button"
          onClick={onRemove}
          className="rounded p-1 text-zinc-600 hover:bg-zinc-700 hover:text-red-400"
        >
          <Trash2 className="size-3.5" />
        </button>
      </div>

      {expanded && (
        <div className="space-y-3 border-t border-zinc-700 px-3 py-3">
          <div className="grid grid-cols-2 gap-3">
            <Field label="Block name" error={errors[`${pfx}.name`]}>
              <TextInput
                value={block.name}
                onChange={(v) => setField("name", v)}
                placeholder="Evening Sitcoms"
                error={!!errors[`${pfx}.name`]}
              />
            </Field>
            <Field label="Content type">
              <NativeSelect
                value={content.type}
                onChange={(v) => setContentType(v as "algorithmic" | "manual")}
              >
                <option value="algorithmic">Algorithmic</option>
                <option value="manual">Manual</option>
              </NativeSelect>
            </Field>
          </div>

          <div className="grid grid-cols-2 gap-3">
            <Field label="Start time">
              <input
                type="time"
                value={block.start_time.slice(0, 5)}
                onChange={(e) => setField("start_time", e.target.value + ":00")}
                className="w-full rounded-md border border-zinc-700 bg-zinc-800 px-3 py-2 text-sm text-zinc-100 focus:border-zinc-500 focus:outline-none"
              />
            </Field>
            <Field label="Duration (minutes)" error={errors[`${pfx}.duration_mins`]}>
              <NumberInput
                value={block.duration_mins}
                onChange={(v) => setField("duration_mins", v === "" ? 60 : v)}
                min={1}
                error={!!errors[`${pfx}.duration_mins`]}
              />
            </Field>
          </div>

          {content.type === "algorithmic" && (
            <>
              <AlgorithmicFilterEditor
                content={content}
                pfx={pfx}
                errors={errors}
                setFilter={setFilter}
                setStrategy={setStrategy}
              />

              {content.strategy === "sequential" && (
                <div className="space-y-2 rounded-md border border-zinc-700/50 bg-zinc-800 p-3">
                  <p className="text-[11px] font-medium uppercase tracking-wider text-zinc-500">
                    Sequential options
                  </p>
                  <label className="flex items-center gap-2 cursor-pointer">
                    <input
                      type="checkbox"
                      checked={block.loop_on_finish ?? true}
                      onChange={(e) => onChange({ ...block, loop_on_finish: e.target.checked })}
                      className="accent-zinc-400"
                    />
                    <span className="text-sm text-zinc-300">Loop series</span>
                    <span className="text-[11px] text-zinc-600">
                      Restart from episode 1 after the final episode
                    </span>
                  </label>
                  <label className="flex items-center gap-2 cursor-pointer">
                    <input
                      type="checkbox"
                      checked={block.ignore_recycle_policy ?? false}
                      onChange={(e) => onChange({ ...block, ignore_recycle_policy: e.target.checked })}
                      className="accent-zinc-400"
                    />
                    <span className="text-sm text-zinc-300">Independent scheduling</span>
                    <span className="text-[11px] text-zinc-600">
                      Play episodes in order even if they aired in another block today
                    </span>
                  </label>
                </div>
              )}
            </>
          )}

          {content.type === "manual" && (
            <div className="space-y-2 rounded-md border border-zinc-700/50 bg-zinc-800 p-3">
              <p className="text-[11px] font-medium uppercase tracking-wider text-zinc-500">Item IDs</p>
              <textarea
                rows={3}
                value={content.items.join("\n")}
                onChange={(e) =>
                  onChange({
                    ...block,
                    content: {
                      type: "manual",
                      items: e.target.value.split("\n").map((s) => s.trim()).filter(Boolean),
                    },
                  })
                }
                placeholder={"abc123\ndef456\nghi789"}
                className="w-full resize-none rounded-md border border-zinc-700 bg-zinc-800 px-3 py-2 font-mono text-xs text-zinc-100 placeholder:text-zinc-600 focus:border-zinc-500 focus:outline-none"
              />
              <p className="text-[11px] text-zinc-600">One Jellyfin item ID per line, played in order.</p>
            </div>
          )}
        </div>
      )}
    </div>
  );
}

// ---------------------------------------------------------------------------
// Recycle policy editor
// ---------------------------------------------------------------------------

function RecyclePolicyEditor({
  policy,
  errors,
  onChange,
}: {
  policy: RecyclePolicy;
  errors: FieldErrors;
  onChange: (policy: RecyclePolicy) => void;
}) {
  return (
    <div className="space-y-3">
      <div className="grid grid-cols-2 gap-3">
        <Field label="Cooldown (days)" hint="Don't replay within N days">
          <NumberInput
            value={policy.cooldown_days ?? ""}
            onChange={(v) => onChange({ ...policy, cooldown_days: v === "" ? null : (v as number) })}
            min={0}
            placeholder="7"
          />
        </Field>
        <Field label="Cooldown (generations)" hint="Don't replay within N schedules">
          <NumberInput
            value={policy.cooldown_generations ?? ""}
            onChange={(v) => onChange({ ...policy, cooldown_generations: v === "" ? null : (v as number) })}
            min={0}
            placeholder="3"
          />
        </Field>
      </div>
      <Field
        label="Min available ratio"
        hint="0.0–1.0 · Fraction of the pool kept selectable even if cooldown is active"
        error={errors["recycle_policy.min_available_ratio"]}
      >
        <NumberInput
          value={policy.min_available_ratio}
          onChange={(v) => onChange({ ...policy, min_available_ratio: v === "" ? 0.1 : (v as number) })}
          min={0}
          max={1}
          step={0.01}
          placeholder="0.1"
          error={!!errors["recycle_policy.min_available_ratio"]}
        />
      </Field>
    </div>
  );
}

// ---------------------------------------------------------------------------
// Main sheet
// ---------------------------------------------------------------------------

interface EditChannelSheetProps {
  channel: ChannelResponse | null;
  open: boolean;
  onOpenChange: (open: boolean) => void;
  onSubmit: (
    id: string,
    data: {
      name: string;
      description: string;
      timezone: string;
      schedule_config: { blocks: ProgrammingBlock[] };
      recycle_policy: RecyclePolicy;
    },
  ) => void;
  isPending: boolean;
  error?: string | null;
}

export function EditChannelSheet({
  channel,
  open,
  onOpenChange,
  onSubmit,
  isPending,
  error,
}: EditChannelSheetProps) {
  const [name, setName] = useState("");
  const [description, setDescription] = useState("");
  const [timezone, setTimezone] = useState("UTC");
  const [blocks, setBlocks] = useState<ProgrammingBlock[]>([]);
  const [recyclePolicy, setRecyclePolicy] = useState<RecyclePolicy>({
    cooldown_days: null,
    cooldown_generations: null,
    min_available_ratio: 0.1,
  });
  const [selectedBlockId, setSelectedBlockId] = useState<string | null>(null);
  const [fieldErrors, setFieldErrors] = useState<FieldErrors>({});

  useEffect(() => {
    if (channel) {
      setName(channel.name);
      setDescription(channel.description ?? "");
      setTimezone(channel.timezone);
      setBlocks(channel.schedule_config.blocks);
      setRecyclePolicy(channel.recycle_policy);
      setSelectedBlockId(null);
      setFieldErrors({});
    }
  }, [channel]);

  const handleSubmit = (e: React.FormEvent) => {
    e.preventDefault();
    if (!channel) return;

    const result = channelFormSchema.safeParse({
      name, description, timezone, blocks, recycle_policy: recyclePolicy,
    });

    if (!result.success) {
      setFieldErrors(extractErrors(result.error));
      return;
    }

    setFieldErrors({});
    onSubmit(channel.id, {
      name,
      description,
      timezone,
      schedule_config: { blocks },
      recycle_policy: recyclePolicy,
    });
  };

  const addBlock = (startMins = 20 * 60, durationMins = 60) => {
    const block = defaultBlock(startMins, durationMins);
    setBlocks((prev) => [...prev, block]);
    setSelectedBlockId(block.id);
  };

  const updateBlock = (idx: number, block: ProgrammingBlock) =>
    setBlocks((prev) => prev.map((b, i) => (i === idx ? block : b)));

  const removeBlock = (idx: number) => {
    setBlocks((prev) => {
      const next = prev.filter((_, i) => i !== idx);
      if (selectedBlockId === prev[idx].id) setSelectedBlockId(null);
      return next;
    });
  };

  return (
    <Sheet open={open} onOpenChange={onOpenChange}>
      <SheetContent
        side="right"
        className="flex w-full flex-col gap-0 border-zinc-800 bg-zinc-900 p-0 text-zinc-100 sm:max-w-2xl"
      >
        <SheetHeader className="border-b border-zinc-800 px-6 py-4">
          <SheetTitle className="text-zinc-100">Edit channel</SheetTitle>
        </SheetHeader>

        <form onSubmit={handleSubmit} className="flex flex-1 flex-col overflow-hidden">
          <div className="flex-1 space-y-6 overflow-y-auto px-6 py-4">
            {/* Basic info */}
            <section className="space-y-3">
              <h3 className="text-xs font-semibold uppercase tracking-wider text-zinc-500">Basic info</h3>

              <Field label="Name" error={fieldErrors["name"]}>
                <TextInput
                  required
                  value={name}
                  onChange={setName}
                  placeholder="90s Sitcom Network"
                  error={!!fieldErrors["name"]}
                />
              </Field>

              <Field label="Timezone" hint="IANA timezone, e.g. America/New_York" error={fieldErrors["timezone"]}>
                <TextInput
                  required
                  value={timezone}
                  onChange={setTimezone}
                  placeholder="UTC"
                  error={!!fieldErrors["timezone"]}
                />
              </Field>

              <Field label="Description">
                <textarea
                  value={description}
                  onChange={(e) => setDescription(e.target.value)}
                  rows={2}
                  placeholder="Nothing but classic sitcoms, all day"
                  className="w-full resize-none rounded-md border border-zinc-700 bg-zinc-800 px-3 py-2 text-sm text-zinc-100 placeholder:text-zinc-600 focus:border-zinc-500 focus:outline-none"
                />
              </Field>
            </section>

            {/* Programming blocks */}
            <section className="space-y-3">
              <div className="flex items-center justify-between">
                <h3 className="text-xs font-semibold uppercase tracking-wider text-zinc-500">
                  Programming blocks
                </h3>
                <Button
                  type="button"
                  variant="outline"
                  size="xs"
                  onClick={() => addBlock()}
                  className="border-zinc-700 text-zinc-300 hover:text-zinc-100"
                >
                  <Plus className="size-3" />
                  Add block
                </Button>
              </div>

              <BlockTimeline
                blocks={blocks}
                selectedId={selectedBlockId}
                onSelect={setSelectedBlockId}
                onChange={setBlocks}
                onCreateBlock={(startMins, durationMins) => addBlock(startMins, durationMins)}
              />

              {blocks.length === 0 && (
                <p className="rounded-md border border-dashed border-zinc-700 px-4 py-6 text-center text-xs text-zinc-600">
                  No blocks yet. Drag on the timeline or click Add block.
                </p>
              )}

              <div className="space-y-2">
                {blocks.map((block, idx) => (
                  <BlockEditor
                    key={block.id}
                    block={block}
                    index={idx}
                    isSelected={block.id === selectedBlockId}
                    color={BLOCK_COLORS[idx % BLOCK_COLORS.length]}
                    errors={fieldErrors}
                    onChange={(b) => updateBlock(idx, b)}
                    onRemove={() => removeBlock(idx)}
                    onSelect={() => setSelectedBlockId(block.id)}
                  />
                ))}
              </div>
            </section>

            {/* Recycle policy */}
            <section className="space-y-3">
              <h3 className="text-xs font-semibold uppercase tracking-wider text-zinc-500">Recycle policy</h3>
              <RecyclePolicyEditor
                policy={recyclePolicy}
                errors={fieldErrors}
                onChange={setRecyclePolicy}
              />
            </section>
          </div>

          {/* Footer */}
          <div className="flex items-center justify-between border-t border-zinc-800 px-6 py-4">
            {(error || Object.keys(fieldErrors).length > 0) && (
              <p className="text-xs text-red-400">
                {error ?? "Please fix the errors above"}
              </p>
            )}
            <div className="ml-auto flex gap-2">
              <Button type="button" variant="ghost" onClick={() => onOpenChange(false)} disabled={isPending}>
                Cancel
              </Button>
              <Button type="submit" disabled={isPending}>
                {isPending ? "Saving…" : "Save changes"}
              </Button>
            </div>
          </div>
        </form>
      </SheetContent>
    </Sheet>
  );
}