package media

import (
	"database/sql"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/mithral/vellum/internal/auth"
)

// listResponse mirrors the JSON contract of handleListItems.
type listResponse struct {
	Items  []itemRow `json:"items"`
	Total  int       `json:"total"`
	Offset int       `json:"offset"`
	Limit  int       `json:"limit"`
}

func listItems(t *testing.T, h *Handlers, u auth.User, query string) (int, listResponse) {
	t.Helper()
	req := httptest.NewRequest(http.MethodGet, "/api/v1/items"+query, nil)
	rec := httptest.NewRecorder()
	h.handleListItems(rec, req, u)
	var resp listResponse
	if rec.Code == http.StatusOK {
		if err := json.Unmarshal(rec.Body.Bytes(), &resp); err != nil {
			t.Fatalf("decode list: %v (body %s)", err, rec.Body.String())
		}
	}
	return rec.Code, resp
}

type listFixture struct {
	db       *sql.DB
	libA     int64
	libB     int64
	userA    int64
	userNone int64
	e1       int64 // libA ebooks, sort 01
	e2       int64 // libA ebooks, sort 02
	e3       int64 // libA ebooks, sort 03
	c1       int64 // libA comics, sort 04
	m1       int64 // libA ebooks, missing
	b1       int64 // libB audiobooks
}

func setupList(t *testing.T) listFixture {
	t.Helper()
	db := testDB(t)
	f := listFixture{db: db}

	f.libA = newLibrary(t, db, "List A", "ebooks", "/list/a")
	f.libB = newLibrary(t, db, "List B", "audiobooks", "/list/b")
	f.userA = newUser(t, db, "list-a")
	f.userNone = newUser(t, db, "list-none")
	grantRead(t, db, f.userA, f.libA)

	const at = "2026-01-01T00:00:00.000Z"
	f.e1 = newItem(t, db, f.libA, "ebooks", "e1.epub", "Echo", "01 echo", false, at)
	f.e2 = newItem(t, db, f.libA, "ebooks", "e2.epub", "Delta", "02 delta", false, at)
	f.e3 = newItem(t, db, f.libA, "ebooks", "e3.epub", "Charlie", "03 charlie", false, at)
	f.c1 = newItem(t, db, f.libA, "comics", "c1.cbz", "Bravo", "04 bravo", false, at)
	f.m1 = newItem(t, db, f.libA, "ebooks", "m1.epub", "Missing", "05 missing", true, at)
	f.b1 = newItem(t, db, f.libB, "audiobooks", "b1.mp3", "Alpha", "06 alpha", false, at)
	return f
}

// TestListItemsTotalIsNotThePage pins the recently added offset/limit/total
// contract: total counts every matching row, independent of the page window.
func TestListItemsTotalIsNotThePage(t *testing.T) {
	f := setupList(t)
	h := mediaHandlers(t, f.db)

	code, resp := listItems(t, h, auth.User{ID: f.userA}, "?limit=2")
	if code != http.StatusOK {
		t.Fatalf("status = %d, want 200", code)
	}
	if resp.Total != 4 {
		t.Errorf("total = %d, want 4 (all matching present rows, not the page)", resp.Total)
	}
	if len(resp.Items) != 2 {
		t.Errorf("page has %d items, want 2", len(resp.Items))
	}
	if resp.Limit != 2 || resp.Offset != 0 {
		t.Errorf("limit/offset = %d/%d, want 2/0", resp.Limit, resp.Offset)
	}
	for _, it := range resp.Items {
		if it.ID == f.m1 {
			t.Error("a missing item was listed")
		}
	}
}

func TestListItemsPaging(t *testing.T) {
	f := setupList(t)
	h := mediaHandlers(t, f.db)
	u := auth.User{ID: f.userA}

	_, p1 := listItems(t, h, u, "?limit=2&offset=0")
	_, p2 := listItems(t, h, u, "?limit=2&offset=2")
	if len(p1.Items) != 2 || len(p2.Items) != 2 {
		t.Fatalf("page sizes = %d/%d, want 2/2", len(p1.Items), len(p2.Items))
	}
	if p1.Offset != 0 || p2.Offset != 2 {
		t.Errorf("offsets = %d/%d, want 0/2", p1.Offset, p2.Offset)
	}

	// Pages must not overlap, and must order by sort_title.
	if p1.Items[0].ID != f.e1 || p1.Items[1].ID != f.e2 {
		t.Errorf("page 1 = %v, want [%d %d]", idsFromRows(p1.Items), f.e1, f.e2)
	}
	if p2.Items[0].ID != f.e3 || p2.Items[1].ID != f.c1 {
		t.Errorf("page 2 = %v, want [%d %d]", idsFromRows(p2.Items), f.e3, f.c1)
	}
	seen := map[int64]bool{}
	for _, it := range append(append([]itemRow{}, p1.Items...), p2.Items...) {
		if seen[it.ID] {
			t.Errorf("item %d appears on both pages", it.ID)
		}
		seen[it.ID] = true
	}

	// A page past the end is empty but still reports the true total.
	_, beyond := listItems(t, h, u, "?limit=2&offset=99")
	if len(beyond.Items) != 0 || beyond.Total != 4 {
		t.Errorf("beyond page: items=%d total=%d, want 0/4", len(beyond.Items), beyond.Total)
	}
}

func TestListItemsFiltersCompose(t *testing.T) {
	f := setupList(t)
	h := mediaHandlers(t, f.db)
	u := auth.User{ID: f.userA}

	_, ebooks := listItems(t, h, u, "?kind=ebooks")
	if ebooks.Total != 3 {
		t.Errorf("kind=ebooks total = %d, want 3", ebooks.Total)
	}
	for _, it := range ebooks.Items {
		if it.Kind != "ebooks" {
			t.Errorf("kind filter returned a %q item", it.Kind)
		}
	}

	_, libA := listItems(t, h, u, "?library_id="+itoa(f.libA))
	if libA.Total != 4 {
		t.Errorf("library_id=%d total = %d, want 4", f.libA, libA.Total)
	}

	// kind and library_id compose (both must hold).
	_, both := listItems(t, h, u, "?kind=ebooks&library_id="+itoa(f.libA))
	if both.Total != 3 {
		t.Errorf("kind+library total = %d, want 3", both.Total)
	}
	for _, it := range both.Items {
		if it.Kind != "ebooks" || it.LibraryID != f.libA {
			t.Errorf("composed filter returned %+v", it)
		}
	}

	// A kind with no items is an empty page, not an error.
	code, none := listItems(t, h, u, "?kind=movies")
	if code != http.StatusOK || none.Total != 0 || len(none.Items) != 0 {
		t.Errorf("unknown kind: status=%d total=%d items=%d", code, none.Total, len(none.Items))
	}
}

func TestListItemsScoping(t *testing.T) {
	f := setupList(t)
	h := mediaHandlers(t, f.db)

	// A user with no grants sees nothing.
	_, none := listItems(t, h, auth.User{ID: f.userNone}, "?limit=100")
	if none.Total != 0 || len(none.Items) != 0 {
		t.Errorf("no-grant user saw total=%d items=%d", none.Total, len(none.Items))
	}

	// Asking explicitly for a library the user cannot read must not leak it.
	code, leak := listItems(t, h, auth.User{ID: f.userA}, "?library_id="+itoa(f.libB)+"&limit=100")
	if code != http.StatusOK {
		t.Fatalf("status = %d, want 200", code)
	}
	if leak.Total != 0 || len(leak.Items) != 0 {
		t.Errorf("user A read library %d: total=%d items=%d", f.libB, leak.Total, len(leak.Items))
	}

	// The unfiltered list contains only the readable library.
	_, all := listItems(t, h, auth.User{ID: f.userA}, "?limit=100")
	for _, it := range all.Items {
		if it.LibraryID != f.libA {
			t.Errorf("item %d leaked from library %d", it.ID, it.LibraryID)
		}
	}
	if containsRowID(all.Items, f.b1) {
		t.Error("user A's list contained another user's item")
	}
}

func TestListItemsInvalidLibraryID(t *testing.T) {
	f := setupList(t)
	h := mediaHandlers(t, f.db)
	for _, q := range []string{"?library_id=abc", "?library_id=-1", "?library_id=0"} {
		code, _ := listItems(t, h, auth.User{ID: f.userA}, q)
		if code != http.StatusBadRequest {
			t.Errorf("%s status = %d, want 400", q, code)
		}
	}
}

func TestListItemsDefaultsAndCaps(t *testing.T) {
	f := setupList(t)
	h := mediaHandlers(t, f.db)
	u := auth.User{ID: f.userA}

	_, def := listItems(t, h, u, "")
	if def.Limit != 300 || def.Offset != 0 {
		t.Errorf("defaults = limit %d offset %d, want 300/0", def.Limit, def.Offset)
	}

	// Out-of-range limit and negative offset fall back to the defaults.
	for _, q := range []string{"?limit=0", "?limit=5000", "?limit=-1"} {
		_, r := listItems(t, h, u, q)
		if r.Limit != 300 {
			t.Errorf("%s limit = %d, want 300", q, r.Limit)
		}
	}
	_, neg := listItems(t, h, u, "?offset=-5")
	if neg.Offset != 0 {
		t.Errorf("negative offset = %d, want 0", neg.Offset)
	}
}

func idsFromRows(rows []itemRow) []int64 {
	out := make([]int64, len(rows))
	for i, r := range rows {
		out[i] = r.ID
	}
	return out
}

func containsRowID(rows []itemRow, id int64) bool {
	for _, r := range rows {
		if r.ID == id {
			return true
		}
	}
	return false
}