package history

import (
	"context"
	"errors"
	"testing"
)

// personaOf returns the stored role binding of a session, failing the test when the
// session is absent from the list.
func personaOf(t *testing.T, st *Store, id string) string {
	t.Helper()
	sessions, err := st.ListSessions(context.Background())
	if err != nil {
		t.Fatalf("list sessions: %v", err)
	}
	for _, m := range sessions {
		if m.ID == id {
			return m.PersonaID
		}
	}
	t.Fatalf("session %q not found in %+v", id, sessions)
	return ""
}

// TestSessionPersonaRoundTrip is design/22 acceptance 1: the session-level role is
// the single source of truth, so a value written through SetSessionPersona must come
// back from both the direct read and the list projection (the DTO the client gets),
// and the main session — which always exists — starts out unbound ('' = inherit the
// global default). An explicit "" clears the binding back to that same state.
func TestSessionPersonaRoundTrip(t *testing.T) {
	t.Parallel()
	st := newStore(t)
	ctx := context.Background()

	if got := personaOf(t, st, MainSessionID); got != "" {
		t.Fatalf("main session persona_id = %q, want '' (inherit the global default)", got)
	}
	if got, err := st.SessionPersona(ctx, MainSessionID); err != nil || got != "" {
		t.Fatalf("SessionPersona(main) = (%q, %v), want ('', nil)", got, err)
	}

	for _, personaID := range []string{"cyrene", "yuki"} {
		if err := st.SetSessionPersona(ctx, MainSessionID, personaID); err != nil {
			t.Fatalf("SetSessionPersona(%s): %v", personaID, err)
		}
		if got, err := st.SessionPersona(ctx, MainSessionID); err != nil || got != personaID {
			t.Fatalf("SessionPersona(main) = (%q, %v), want (%q, nil)", got, err, personaID)
		}
		if got := personaOf(t, st, MainSessionID); got != personaID {
			t.Fatalf("ListSessions persona_id = %q, want %q", got, personaID)
		}
	}

	// An explicit empty value is the documented "unbind" (follow the default again),
	// not a no-op.
	if err := st.SetSessionPersona(ctx, MainSessionID, ""); err != nil {
		t.Fatalf("SetSessionPersona(\"\"): %v", err)
	}
	if got := personaOf(t, st, MainSessionID); got != "" {
		t.Fatalf("after unbind persona_id = %q, want ''", got)
	}
}

// TestSessionPersonaUnknownSession covers the error contract: binding or reading the
// role of a session that does not exist reports ErrSessionNotFound (so the HTTP layer
// answers 404) instead of silently creating/looking up nothing.
func TestSessionPersonaUnknownSession(t *testing.T) {
	t.Parallel()
	st := newStore(t)
	ctx := context.Background()

	if err := st.SetSessionPersona(ctx, "web:missing", "cyrene"); !errors.Is(err, ErrSessionNotFound) {
		t.Fatalf("SetSessionPersona(missing) err = %v, want ErrSessionNotFound", err)
	}
	if _, err := st.SessionPersona(ctx, "web:missing"); !errors.Is(err, ErrSessionNotFound) {
		t.Fatalf("SessionPersona(missing) err = %v, want ErrSessionNotFound", err)
	}
}

// TestNewSubSessionForBindsPersona locks the create path: a sub session created with a
// role carries it from its first read (no extra PATCH needed), and the plain
// NewSubSession still creates an unbound session — the pre-multi-character contract,
// which every existing caller relies on.
func TestNewSubSessionForBindsPersona(t *testing.T) {
	t.Parallel()
	st := newStore(t)
	ctx := context.Background()

	bound, err := st.NewSubSessionFor(ctx, "owner", "yuki")
	if err != nil {
		t.Fatalf("NewSubSessionFor: %v", err)
	}
	if got := personaOf(t, st, bound); got != "yuki" {
		t.Fatalf("bound sub persona_id = %q, want yuki", got)
	}

	plain, err := st.NewSubSession(ctx, "owner")
	if err != nil {
		t.Fatalf("NewSubSession: %v", err)
	}
	if got := personaOf(t, st, plain); got != "" {
		t.Fatalf("plain sub persona_id = %q, want ''", got)
	}
}

// TestMessagePersonaPersisted proves design/22 §7-5's storage half: a session may
// switch roles while keeping its context, so every message records the role that
// SPOKE it. The column survives the write/read round trip through the same scanner
// the REST/WS DTOs use, and messages written without a role stay '' (= the default
// role), which is what keeps pre-upgrade history readable.
func TestMessagePersonaPersisted(t *testing.T) {
	t.Parallel()
	st := newStore(t)
	ctx := context.Background()

	if err := st.Append(ctx, Message{SessionID: MainSessionID, Role: RoleUser, Content: "yuki 你好", PersonaID: "yuki"}); err != nil {
		t.Fatalf("append with persona: %v", err)
	}
	if err := st.Append(ctx, Message{SessionID: MainSessionID, Role: RoleAssistant, Content: "在～"}); err != nil {
		t.Fatalf("append without persona: %v", err)
	}

	msgs, err := st.List(ctx, MainSessionID, 0, 10, "")
	if err != nil {
		t.Fatalf("list: %v", err)
	}
	if len(msgs) != 2 {
		t.Fatalf("listed %d messages, want 2", len(msgs))
	}
	byRole := map[string]string{}
	for _, m := range msgs {
		byRole[m.Role] = m.PersonaID
	}
	if got := byRole[RoleUser]; got != "yuki" {
		t.Fatalf("user message persona_id = %q, want yuki", got)
	}
	if got := byRole[RoleAssistant]; got != "" {
		t.Fatalf("unattributed message persona_id = %q, want ''", got)
	}

	// The persona column must also survive Recent (the WS replay path) and
	// AppendFull (the orchestrator's realtime-sync path).
	recent, err := st.Recent(ctx, MainSessionID, 10)
	if err != nil {
		t.Fatalf("recent: %v", err)
	}
	found := false
	for _, m := range recent {
		if m.PersonaID == "yuki" {
			found = true
		}
	}
	if !found {
		t.Fatalf("Recent lost the message persona: %+v", recent)
	}

	full, err := st.AppendFull(ctx, Message{SessionID: MainSessionID, Role: RoleAssistant, Content: "记住了", PersonaID: "yuki"})
	if err != nil {
		t.Fatalf("append full: %v", err)
	}
	if full.PersonaID != "yuki" {
		t.Fatalf("AppendFull returned persona_id = %q, want yuki", full.PersonaID)
	}
	after, err := st.ListAfter(ctx, MainSessionID, 0, 10, "")
	if err != nil {
		t.Fatalf("list after: %v", err)
	}
	if len(after) == 0 || after[len(after)-1].PersonaID != "yuki" {
		t.Fatalf("ListAfter lost the message persona: %+v", after)
	}
}