package api

import (
	"context"
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"strconv"
	"strings"
	"testing"

	"git.fabledsword.com/bvandeusen/minstrel/internal/auth"
	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
	"git.fabledsword.com/bvandeusen/minstrel/internal/sync"
)

func callLibrarySync(h *handlers, user dbq.User, since string) *httptest.ResponseRecorder {
	url := "/api/library/sync"
	if since != "" {
		url += "?since=" + since
	}
	req := httptest.NewRequest(http.MethodGet, url, nil)
	req = req.WithContext(context.WithValue(req.Context(), auth.UserCtxKeyForTest(), user))
	w := httptest.NewRecorder()
	h.handleLibrarySync(w, req)
	return w
}

func TestLibrarySync_NoChanges_Returns204(t *testing.T) {
	h, pool := testHandlers(t)
	truncateLibrary(t, pool)
	u := seedUser(t, pool, "alice", "x", false)

	w := callLibrarySync(h, u, "0")
	if w.Code != http.StatusNoContent {
		t.Fatalf("status = %d body = %s", w.Code, w.Body.String())
	}
}

func TestLibrarySync_AfterArtistUpsert_ReturnsHydratedPayload(t *testing.T) {
	h, pool := testHandlers(t)
	truncateLibrary(t, pool)
	u := seedUser(t, pool, "alice", "x", false)

	// Seed an artist + write a change row in the same tx — the invariant
	// library writes keep, and the handler relies on.
	ctx := context.Background()
	tx, err := pool.Begin(ctx)
	if err != nil {
		t.Fatalf("begin: %v", err)
	}
	defer func() { _ = tx.Rollback(ctx) }()
	var artistID string
	if err := tx.QueryRow(ctx,
		`INSERT INTO artists (name, sort_name) VALUES ($1, $2) RETURNING id::text`,
		"Boards of Canada", "Boards of Canada",
	).Scan(&artistID); err != nil {
		t.Fatalf("insert artist: %v", err)
	}
	if err := sync.LogChange(ctx, tx, sync.EntityArtist, artistID, sync.OpUpsert); err != nil {
		t.Fatalf("LogChange: %v", err)
	}
	if err := tx.Commit(ctx); err != nil {
		t.Fatalf("commit: %v", err)
	}

	w := callLibrarySync(h, u, "0")
	if w.Code != http.StatusOK {
		t.Fatalf("status = %d body = %s", w.Code, w.Body.String())
	}
	var body struct {
		Cursor  int64                        `json:"cursor"`
		Upserts map[string][]json.RawMessage `json:"upserts"`
		Deletes map[string][]string          `json:"deletes"`
	}
	if err := json.NewDecoder(w.Body).Decode(&body); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if body.Cursor <= 0 {
		t.Fatalf("expected positive cursor, got %d", body.Cursor)
	}
	if len(body.Upserts["artist"]) != 1 {
		t.Fatalf("expected 1 artist upsert, got %d", len(body.Upserts["artist"]))
	}
}

func TestLibrarySync_CursorMonotonic(t *testing.T) {
	h, pool := testHandlers(t)
	truncateLibrary(t, pool)
	u := seedUser(t, pool, "alice", "x", false)

	ctx := context.Background()
	tx, _ := pool.Begin(ctx)
	var artistID string
	_ = tx.QueryRow(ctx,
		`INSERT INTO artists (name, sort_name) VALUES ($1, $2) RETURNING id::text`,
		"A", "A",
	).Scan(&artistID)
	_ = sync.LogChange(ctx, tx, sync.EntityArtist, artistID, sync.OpUpsert)
	_ = tx.Commit(ctx)

	w1 := callLibrarySync(h, u, "0")
	if w1.Code != http.StatusOK {
		t.Fatalf("first call status = %d", w1.Code)
	}
	var body1 struct {
		Cursor int64 `json:"cursor"`
	}
	if err := json.NewDecoder(w1.Body).Decode(&body1); err != nil {
		t.Fatalf("decode: %v", err)
	}

	w2 := callLibrarySync(h, u, strconv.FormatInt(body1.Cursor, 10))
	if w2.Code != http.StatusNoContent {
		t.Fatalf("second call status = %d body = %s", w2.Code, w2.Body.String())
	}
}

func TestLibrarySync_DeleteIsReflected(t *testing.T) {
	h, pool := testHandlers(t)
	truncateLibrary(t, pool)
	u := seedUser(t, pool, "alice", "x", false)

	// Just write a delete change row directly (no underlying mutation).
	// Library writes couple real deletes to LogChange; here we test the
	// handler reflects what's in the log.
	ctx := context.Background()
	tx, _ := pool.Begin(ctx)
	_ = sync.LogChange(ctx, tx, sync.EntityArtist, "deadbeef-dead-beef-dead-beefdeadbeef", sync.OpDelete)
	_ = tx.Commit(ctx)

	w := callLibrarySync(h, u, "0")
	if w.Code != http.StatusOK {
		t.Fatalf("status = %d body = %s", w.Code, w.Body.String())
	}
	var body struct {
		Cursor  int64                        `json:"cursor"`
		Upserts map[string][]json.RawMessage `json:"upserts"`
		Deletes map[string][]string          `json:"deletes"`
	}
	if err := json.NewDecoder(w.Body).Decode(&body); err != nil {
		t.Fatalf("decode: %v", err)
	}
	if got := body.Deletes["artist"]; len(got) != 1 || got[0] != "deadbeef-dead-beef-dead-beefdeadbeef" {
		t.Fatalf("expected one artist delete; got %#v", body.Deletes)
	}
}

func TestLibrarySync_LikeRowScopedToUser(t *testing.T) {
	h, pool := testHandlers(t)
	truncateLibrary(t, pool)
	u := seedUser(t, pool, "alice", "x", false)
	other := seedUser(t, pool, "bob", "x", false)

	// Two like_track rows: one for u, one for other. u's call should
	// see only their own row.
	ctx := context.Background()
	tx, _ := pool.Begin(ctx)
	_ = sync.LogChange(ctx, tx, sync.EntityLikeTrack,
		sync.EncodeLikeID(sync.FormatUUID(u.ID), "11111111-1111-1111-1111-111111111111"),
		sync.OpUpsert)
	_ = sync.LogChange(ctx, tx, sync.EntityLikeTrack,
		sync.EncodeLikeID(sync.FormatUUID(other.ID), "22222222-2222-2222-2222-222222222222"),
		sync.OpUpsert)
	_ = tx.Commit(ctx)

	w := callLibrarySync(h, u, "0")
	if w.Code != http.StatusOK {
		t.Fatalf("status = %d body = %s", w.Code, w.Body.String())
	}
	var body struct {
		Upserts map[string][]json.RawMessage `json:"upserts"`
	}
	if err := json.NewDecoder(w.Body).Decode(&body); err != nil {
		t.Fatalf("decode: %v", err)
	}
	got := body.Upserts["like_track"]
	if len(got) != 1 {
		t.Fatalf("expected 1 like row scoped to alice, got %d", len(got))
	}
}

// Pure unit tests below — run even with -short.

func TestSplitOnce(t *testing.T) {
	cases := []struct {
		in, sep string
		want    []string
	}{
		{"a:b", ":", []string{"a", "b"}},
		{"a:b:c", ":", []string{"a", "b:c"}},
		{"abc", ":", []string{"abc"}},
		{":x", ":", []string{"", "x"}},
	}
	for _, c := range cases {
		got := splitOnce(c.in, c.sep)
		if len(got) != len(c.want) {
			t.Errorf("splitOnce(%q,%q): len got=%d want=%d", c.in, c.sep, len(got), len(c.want))
			continue
		}
		for i := range got {
			if got[i] != c.want[i] {
				t.Errorf("splitOnce(%q,%q)[%d] = %q want %q", c.in, c.sep, i, got[i], c.want[i])
			}
		}
	}
}

// A server restored from an older backup has handed out fewer cursors than an
// app remembers; the app is told to reset rather than wait for ids it would
// then skip. A compacted log is not that: the cursor the server handed out
// still counts.
func TestLibrarySync_ACursorPastTheServersLastChangeIsReset(t *testing.T) {
	h, pool := testHandlers(t)
	truncateLibrary(t, pool)
	u := seedUser(t, pool, "alice", "x", false)

	ctx := context.Background()
	var artistID string
	if err := pool.QueryRow(ctx,
		`INSERT INTO artists (name, sort_name) VALUES ('A', 'A') RETURNING id::text`).Scan(&artistID); err != nil {
		t.Fatal(err)
	}
	tx, err := pool.Begin(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if err := sync.LogChange(ctx, tx, sync.EntityArtist, artistID, sync.OpUpsert); err != nil {
		t.Fatal(err)
	}
	if err := tx.Commit(ctx); err != nil {
		t.Fatal(err)
	}
	var last int64
	if err := pool.QueryRow(ctx, `SELECT max(id) FROM library_changes`).Scan(&last); err != nil {
		t.Fatal(err)
	}

	w := callLibrarySync(h, u, strconv.FormatInt(last+50, 10))
	if w.Code != http.StatusGone || !strings.Contains(w.Body.String(), "cursor_ahead") {
		t.Errorf("a cursor past the last change: status = %d body = %s, want 410 cursor_ahead", w.Code, w.Body.String())
	}

	// The compactor trims every row; the app's cursor is still one this
	// server handed out.
	if _, err := pool.Exec(ctx, `DELETE FROM library_changes`); err != nil {
		t.Fatal(err)
	}
	if w := callLibrarySync(h, u, strconv.FormatInt(last, 10)); w.Code != http.StatusNoContent {
		t.Errorf("the last cursor after compaction: status = %d body = %s, want 204", w.Code, w.Body.String())
	}
}

// An app is sent back to 0 only when its cursor is below a delete the log has
// dropped, which it may have missed. A cursor at that delete has seen it, and
// one between dropped and kept rows replays what is still there.
func TestLibrarySync_ACursorBelowADroppedDeleteIsReset(t *testing.T) {
	h, pool := testHandlers(t)
	truncateLibrary(t, pool)
	u := seedUser(t, pool, "alice", "x", false)
	ctx := context.Background()

	for i := 0; i < 5; i++ {
		if _, err := pool.Exec(ctx, `INSERT INTO library_changes (entity_type, entity_id, op) VALUES ('artist', $1, 'upsert')`,
			strconv.Itoa(i)); err != nil {
			t.Fatal(err)
		}
	}
	var dropped int64
	if err := pool.QueryRow(ctx, `SELECT min(id) + 2 FROM library_changes`).Scan(&dropped); err != nil {
		t.Fatal(err)
	}
	if _, err := pool.Exec(ctx, `UPDATE library_changes_trimmed SET through = $1`, dropped); err != nil {
		t.Fatal(err)
	}

	if w := callLibrarySync(h, u, strconv.FormatInt(dropped-1, 10)); w.Code != http.StatusGone ||
		!strings.Contains(w.Body.String(), "cursor_too_old") {
		t.Errorf("a cursor below the dropped delete: status = %d body = %s, want 410 cursor_too_old", w.Code, w.Body.String())
	}
	if w := callLibrarySync(h, u, strconv.FormatInt(dropped, 10)); w.Code != http.StatusOK {
		t.Errorf("a cursor at the dropped delete: status = %d body = %s, want 200", w.Code, w.Body.String())
	}
	if w := callLibrarySync(h, u, "0"); w.Code != http.StatusOK {
		t.Errorf("a sync from 0: status = %d body = %s, want 200", w.Code, w.Body.String())
	}
}