import { useState, useMemo } from "react";
import { useParams, Link } from "react-router-dom";
import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
import { getBand } from "../api/bands";
import { api } from "../api/client";

interface SongSummary {
  id: string;
  title: string;
  status: string;
  tags: string[];
  global_key: string | null;
  global_bpm: number | null;
  version_count: number;
}

interface SessionSummary {
  id: string;
  date: string;
  label: string | null;
  recording_count: number;
}

type FilterPill = "all" | "full band" | "guitar" | "vocals" | "drums" | "keys" | "commented";

const PILLS: FilterPill[] = ["all", "full band", "guitar", "vocals", "drums", "keys", "commented"];

function formatDate(iso: string): string {
  const d = new Date(iso.slice(0, 10) + "T12:00:00");
  return d.toLocaleDateString(undefined, { year: "numeric", month: "short", day: "numeric" });
}

function formatDateLabel(iso: string): string {
  const d = new Date(iso.slice(0, 10) + "T12:00:00");
  const today = new Date();
  today.setHours(12, 0, 0, 0);
  const diffDays = Math.round((today.getTime() - d.getTime()) / (1000 * 60 * 60 * 24));
  if (diffDays === 0) {
    return "Today — " + d.toLocaleDateString(undefined, { month: "short", day: "numeric" });
  }
  return d.toLocaleDateString(undefined, { month: "short", day: "numeric" });
}

export function BandPage() {
  const { bandId } = useParams<{ bandId: string }>();
  const qc = useQueryClient();
  const [showCreate, setShowCreate] = useState(false);
  const [newTitle, setNewTitle] = useState("");
  const [error, setError] = useState<string | null>(null);
  const [scanning, setScanning] = useState(false);
  const [scanProgress, setScanProgress] = useState<string | null>(null);
  const [scanMsg, setScanMsg] = useState<string | null>(null);
  const [librarySearch, setLibrarySearch] = useState("");
  const [activePill, setActivePill] = useState<FilterPill>("all");

  const { data: band, isLoading } = useQuery({
    queryKey: ["band", bandId],
    queryFn: () => getBand(bandId!),
    enabled: !!bandId,
  });

  const { data: sessions } = useQuery({
    queryKey: ["sessions", bandId],
    queryFn: () => api.get<SessionSummary[]>(`/bands/${bandId}/sessions`),
    enabled: !!bandId,
  });

  const { data: unattributedSongs } = useQuery({
    queryKey: ["songs-unattributed", bandId],
    queryFn: () => api.get<SongSummary[]>(`/bands/${bandId}/songs/search?unattributed=true`),
    enabled: !!bandId,
  });

  const filteredSessions = useMemo(() => {
    return (sessions ?? []).filter((s) => {
      if (!librarySearch) return true;
      const haystack = [s.label ?? "", s.date, formatDate(s.date)].join(" ").toLowerCase();
      return haystack.includes(librarySearch.toLowerCase());
    });
  }, [sessions, librarySearch]);

  const filteredUnattributed = useMemo(() => {
    return (unattributedSongs ?? []).filter((song) => {
      const matchesSearch =
        !librarySearch || song.title.toLowerCase().includes(librarySearch.toLowerCase());
      const matchesPill =
        activePill === "all" ||
        activePill === "commented" ||
        song.tags.some((t) => t.toLowerCase() === activePill);
      return matchesSearch && matchesPill;
    });
  }, [unattributedSongs, librarySearch, activePill]);

  const createMutation = useMutation({
    mutationFn: () => api.post(`/bands/${bandId}/songs`, { title: newTitle }),
    onSuccess: () => {
      qc.invalidateQueries({ queryKey: ["sessions", bandId] });
      setShowCreate(false);
      setNewTitle("");
      setError(null);
    },
    onError: (err) => setError(err instanceof Error ? err.message : "Failed to create song"),
  });

  async function startScan() {
    if (scanning || !bandId) return;
    setScanning(true);
    setScanMsg(null);
    setScanProgress("Starting scan…");

    const url = `/api/v1/bands/${bandId}/nc-scan/stream`;

    try {
      const resp = await fetch(url, { credentials: "include" });
      if (!resp.ok || !resp.body) {
        const text = await resp.text().catch(() => resp.statusText);
        throw new Error(text || `HTTP ${resp.status}`);
      }

      const reader = resp.body.getReader();
      const decoder = new TextDecoder();
      let buf = "";

      while (true) {
        const { done, value } = await reader.read();
        if (done) break;
        buf += decoder.decode(value, { stream: true });
        const lines = buf.split("\n");
        buf = lines.pop() ?? "";

        for (const line of lines) {
          if (!line.trim()) continue;
          let event: Record<string, unknown>;
          try { event = JSON.parse(line); } catch { continue; }

          if (event.type === "progress") {
            setScanProgress(event.message as string);
          } else if (event.type === "song" || event.type === "session") {
            qc.invalidateQueries({ queryKey: ["sessions", bandId] });
            qc.invalidateQueries({ queryKey: ["songs-unattributed", bandId] });
          } else if (event.type === "done") {
            const s = event.stats as { found: number; imported: number; skipped: number };
            if (s.imported > 0) {
              setScanMsg(`Imported ${s.imported} new song${s.imported !== 1 ? "s" : ""} (${s.skipped} already registered).`);
            } else if (s.found === 0) {
              setScanMsg("No audio files found.");
            } else {
              setScanMsg(`All ${s.found} file${s.found !== 1 ? "s" : ""} already registered.`);
            }
            setTimeout(() => setScanMsg(null), 6000);
          } else if (event.type === "error") {
            setScanMsg(`Scan error: ${event.message}`);
          }
        }
      }
    } catch (err) {
      setScanMsg(err instanceof Error ? err.message : "Scan failed");
    } finally {
      setScanning(false);
      setScanProgress(null);
    }
  }

  if (isLoading) return <div style={{ color: "var(--text-muted)", padding: 32 }}>Loading...</div>;
  if (!band) return <div style={{ color: "var(--danger)", padding: 32 }}>Band not found</div>;

  const hasResults = filteredSessions.length > 0 || filteredUnattributed.length > 0;

  return (
    <div style={{ display: "flex", flexDirection: "column", height: "100%", maxWidth: 760, margin: "0 auto" }}>

      {/* ── Header ─────────────────────────────────────────────── */}
      <div style={{ padding: "18px 26px 0", flexShrink: 0, borderBottom: "1px solid rgba(255,255,255,0.06)" }}>
        {/* Title row + search + actions */}
        <div style={{ display: "flex", alignItems: "center", gap: 10, marginBottom: 11 }}>
          <h1 style={{ fontSize: 17, fontWeight: 500, color: "#eeeef2", margin: 0, flexShrink: 0 }}>
            Library
          </h1>

          {/* Search input */}
          <div style={{ position: "relative", flex: 1, maxWidth: 280 }}>
            <svg
              style={{ position: "absolute", left: 10, top: "50%", transform: "translateY(-50%)", opacity: 0.3, pointerEvents: "none", color: "#eeeef2" }}
              width="13" height="13" viewBox="0 0 13 13" fill="none" stroke="currentColor" strokeWidth="1.5"
            >
              <circle cx="5.5" cy="5.5" r="3.5" />
              <path d="M8.5 8.5l3 3" strokeLinecap="round" />
            </svg>
            <input
              value={librarySearch}
              onChange={(e) => setLibrarySearch(e.target.value)}
              placeholder="Search recordings, comments…"
              style={{
                width: "100%",
                padding: "7px 12px 7px 30px",
                background: "rgba(255,255,255,0.05)",
                border: "1px solid rgba(255,255,255,0.08)",
                borderRadius: 7,
                color: "#e2e2e8",
                fontSize: 13,
                fontFamily: "inherit",
                outline: "none",
                boxSizing: "border-box",
              }}
              onFocus={(e) => (e.currentTarget.style.borderColor = "rgba(232,162,42,0.35)")}
              onBlur={(e) => (e.currentTarget.style.borderColor = "rgba(255,255,255,0.08)")}
            />
          </div>

          <div style={{ marginLeft: "auto", display: "flex", gap: 8, flexShrink: 0 }}>
            <button
              onClick={startScan}
              disabled={scanning}
              style={{
                background: "none",
                border: "1px solid rgba(255,255,255,0.09)",
                borderRadius: 6,
                color: scanning ? "rgba(255,255,255,0.28)" : "#4dba85",
                cursor: scanning ? "default" : "pointer",
                padding: "5px 12px",
                fontSize: 12,
                fontFamily: "inherit",
              }}
            >
              {scanning ? "Scanning…" : "⟳ Scan Nextcloud"}
            </button>
            <button
              onClick={() => { setShowCreate(!showCreate); setError(null); }}
              style={{
                background: "rgba(232,162,42,0.14)",
                border: "1px solid rgba(232,162,42,0.28)",
                borderRadius: 6,
                color: "#e8a22a",
                cursor: "pointer",
                padding: "5px 12px",
                fontSize: 12,
                fontWeight: 600,
                fontFamily: "inherit",
              }}
            >
              + Upload
            </button>
          </div>
        </div>

        {/* Filter pills */}
        <div style={{ display: "flex", gap: 5, flexWrap: "wrap", paddingBottom: 14 }}>
          {PILLS.map((pill) => {
            const active = activePill === pill;
            return (
              <button
                key={pill}
                onClick={() => setActivePill(pill)}
                style={{
                  padding: "3px 10px",
                  borderRadius: 20,
                  cursor: "pointer",
                  border: `1px solid ${active ? "rgba(232,162,42,0.28)" : "rgba(255,255,255,0.08)"}`,
                  background: active ? "rgba(232,162,42,0.1)" : "transparent",
                  color: active ? "#e8a22a" : "rgba(255,255,255,0.3)",
                  fontSize: 11,
                  fontFamily: "inherit",
                  transition: "all 0.12s",
                  textTransform: "capitalize",
                }}
              >
                {pill}
              </button>
            );
          })}
        </div>
      </div>

      {/* ── Scan feedback ─────────────────────────────────────── */}
      {scanning && scanProgress && (
        <div style={{ padding: "10px 26px 0", flexShrink: 0 }}>
          <div style={{ background: "rgba(255,255,255,0.03)", border: "1px solid rgba(255,255,255,0.07)", borderRadius: 8, color: "rgba(255,255,255,0.42)", fontSize: 12, padding: "8px 14px", fontFamily: "monospace" }}>
            {scanProgress}
          </div>
        </div>
      )}
      {scanMsg && (
        <div style={{ padding: "10px 26px 0", flexShrink: 0 }}>
          <div style={{ background: "rgba(61,200,120,0.06)", border: "1px solid rgba(61,200,120,0.25)", borderRadius: 8, color: "#4dba85", fontSize: 12, padding: "8px 14px" }}>
            {scanMsg}
          </div>
        </div>
      )}

      {/* ── New song / upload form ─────────────────────────────── */}
      {showCreate && (
        <div style={{ padding: "14px 26px 0", flexShrink: 0 }}>
          <div style={{ background: "rgba(255,255,255,0.025)", border: "1px solid rgba(255,255,255,0.07)", borderRadius: 8, padding: 18 }}>
            {error && <p style={{ color: "#e07070", fontSize: 13, marginBottom: 12 }}>{error}</p>}
            <label style={{ display: "block", color: "rgba(255,255,255,0.28)", fontSize: 11, letterSpacing: "0.6px", textTransform: "uppercase", marginBottom: 6 }}>
              Song title
            </label>
            <input
              value={newTitle}
              onChange={(e) => setNewTitle(e.target.value)}
              onKeyDown={(e) => e.key === "Enter" && newTitle && createMutation.mutate()}
              style={{ width: "100%", padding: "8px 12px", background: "rgba(255,255,255,0.05)", border: "1px solid rgba(255,255,255,0.08)", borderRadius: 7, color: "#eeeef2", marginBottom: 12, fontSize: 14, fontFamily: "inherit", boxSizing: "border-box", outline: "none" }}
              autoFocus
            />
            <div style={{ display: "flex", gap: 8 }}>
              <button
                onClick={() => createMutation.mutate()}
                disabled={!newTitle}
                style={{ background: "rgba(232,162,42,0.14)", border: "1px solid rgba(232,162,42,0.28)", borderRadius: 6, color: "#e8a22a", cursor: newTitle ? "pointer" : "default", padding: "7px 18px", fontWeight: 600, fontSize: 13, fontFamily: "inherit", opacity: newTitle ? 1 : 0.4 }}
              >
                Create
              </button>
              <button
                onClick={() => { setShowCreate(false); setError(null); }}
                style={{ background: "none", border: "1px solid rgba(255,255,255,0.09)", borderRadius: 6, color: "rgba(255,255,255,0.42)", cursor: "pointer", padding: "7px 18px", fontSize: 13, fontFamily: "inherit" }}
              >
                Cancel
              </button>
            </div>
          </div>
        </div>
      )}

      {/* ── Scrollable content ────────────────────────────────── */}
      <div style={{ flex: 1, overflowY: "auto", padding: "4px 26px 26px" }}>

        {/* Sessions — one date group per session */}
        {filteredSessions.map((s) => (
          <div key={s.id} style={{ marginTop: 18 }}>
            {/* Date group header */}
            <div style={{ display: "flex", alignItems: "center", gap: 10, marginBottom: 8 }}>
              <span style={{ fontSize: 10, fontWeight: 500, color: "rgba(255,255,255,0.32)", textTransform: "uppercase", letterSpacing: "0.6px", whiteSpace: "nowrap" }}>
                {formatDateLabel(s.date)}{s.label ? ` — ${s.label}` : ""}
              </span>
              <div style={{ flex: 1, height: 1, background: "rgba(255,255,255,0.05)" }} />
              <span style={{ fontSize: 10, color: "rgba(255,255,255,0.18)", whiteSpace: "nowrap" }}>
                {s.recording_count} recording{s.recording_count !== 1 ? "s" : ""}
              </span>
            </div>

            {/* Session row */}
            <Link
              to={`/bands/${bandId}/sessions/${s.id}`}
              style={{
                display: "flex",
                alignItems: "center",
                gap: 11,
                padding: "9px 13px",
                borderRadius: 8,
                background: "rgba(255,255,255,0.02)",
                border: "1px solid rgba(255,255,255,0.04)",
                textDecoration: "none",
                cursor: "pointer",
                transition: "background 0.12s, border-color 0.12s",
              }}
              onMouseEnter={(e) => {
                (e.currentTarget as HTMLElement).style.background = "rgba(255,255,255,0.048)";
                (e.currentTarget as HTMLElement).style.borderColor = "rgba(255,255,255,0.08)";
              }}
              onMouseLeave={(e) => {
                (e.currentTarget as HTMLElement).style.background = "rgba(255,255,255,0.02)";
                (e.currentTarget as HTMLElement).style.borderColor = "rgba(255,255,255,0.04)";
              }}
            >
              {/* Session name */}
              <span style={{ flex: 1, fontSize: 13, color: "#c8c8d0", fontFamily: "'SF Mono','Fira Code',monospace", overflow: "hidden", textOverflow: "ellipsis", whiteSpace: "nowrap" }}>
                {s.label ?? formatDate(s.date)}
              </span>

              {/* Recording count */}
              <span style={{ fontSize: 11, color: "rgba(255,255,255,0.28)", whiteSpace: "nowrap", flexShrink: 0 }}>
                {s.recording_count}
              </span>
            </Link>
          </div>
        ))}

        {/* Unattributed recordings */}
        {filteredUnattributed.length > 0 && (
          <div style={{ marginTop: filteredSessions.length > 0 ? 28 : 18 }}>
            {/* Section header */}
            <div style={{ display: "flex", alignItems: "center", gap: 10, marginBottom: 8 }}>
              <span style={{ fontSize: 10, fontWeight: 500, color: "rgba(255,255,255,0.32)", textTransform: "uppercase", letterSpacing: "0.6px", whiteSpace: "nowrap" }}>
                Unattributed
              </span>
              <div style={{ flex: 1, height: 1, background: "rgba(255,255,255,0.05)" }} />
              <span style={{ fontSize: 10, color: "rgba(255,255,255,0.18)", whiteSpace: "nowrap" }}>
                {filteredUnattributed.length} track{filteredUnattributed.length !== 1 ? "s" : ""}
              </span>
            </div>

            <div style={{ display: "grid", gap: 3 }}>
              {filteredUnattributed.map((song) => (
                <Link
                  key={song.id}
                  to={`/bands/${bandId}/songs/${song.id}`}
                  style={{ display: "flex", alignItems: "center", gap: 11, padding: "9px 13px", borderRadius: 8, background: "rgba(255,255,255,0.02)", border: "1px solid rgba(255,255,255,0.04)", textDecoration: "none", transition: "background 0.12s, border-color 0.12s" }}
                  onMouseEnter={(e) => {
                    (e.currentTarget as HTMLElement).style.background = "rgba(255,255,255,0.048)";
                    (e.currentTarget as HTMLElement).style.borderColor = "rgba(255,255,255,0.08)";
                  }}
                  onMouseLeave={(e) => {
                    (e.currentTarget as HTMLElement).style.background = "rgba(255,255,255,0.02)";
                    (e.currentTarget as HTMLElement).style.borderColor = "rgba(255,255,255,0.04)";
                  }}
                >
                  <div style={{ flex: 1, minWidth: 0 }}>
                    <div style={{ fontSize: 13, color: "#c8c8d0", fontFamily: "'SF Mono','Fira Code',monospace", overflow: "hidden", textOverflow: "ellipsis", whiteSpace: "nowrap", marginBottom: 3 }}>
                      {song.title}
                    </div>
                    <div style={{ display: "flex", gap: 4, flexWrap: "wrap" }}>
                      {song.tags.map((t) => (
                        <span key={t} style={{ background: "rgba(61,200,120,0.08)", color: "#4dba85", fontSize: 9, padding: "1px 6px", borderRadius: 3, fontFamily: "monospace" }}>
                          {t}
                        </span>
                      ))}
                      {song.global_key && (
                        <span style={{ background: "rgba(255,255,255,0.05)", color: "rgba(255,255,255,0.28)", fontSize: 9, padding: "1px 6px", borderRadius: 3, fontFamily: "monospace" }}>
                          {song.global_key}
                        </span>
                      )}
                      {song.global_bpm && (
                        <span style={{ background: "rgba(255,255,255,0.05)", color: "rgba(255,255,255,0.28)", fontSize: 9, padding: "1px 6px", borderRadius: 3, fontFamily: "monospace" }}>
                          {song.global_bpm.toFixed(0)} BPM
                        </span>
                      )}
                    </div>
                  </div>

                  <span style={{ fontSize: 11, color: "rgba(255,255,255,0.28)", whiteSpace: "nowrap", flexShrink: 0 }}>
                    {song.version_count} ver{song.version_count !== 1 ? "s" : ""}
                  </span>
                </Link>
              ))}
            </div>
          </div>
        )}

        {/* Empty state */}
        {!hasResults && (
          <p style={{ color: "rgba(255,255,255,0.28)", fontSize: 13, padding: "24px 0 8px" }}>
            {librarySearch
              ? "No results match your search."
              : "No sessions yet. Scan Nextcloud or create a song to get started."}
          </p>
        )}
      </div>
    </div>
  );
}

