package mail

import (
	"errors"
	"testing"

	"thuanle.me/claw-email-bridge/internal/database"
)

func TestResolveThreadID_NoHeaders_ReturnsMessageID(t *testing.T) {
	got := resolveThreadID("msg-1", "", "", nilLookup)
	if got != "msg-1" {
		t.Fatalf("expected msg-1, got %s", got)
	}
}

func TestResolveThreadID_InReplyToMatches_ReturnsParentThreadID(t *testing.T) {
	lookup := func(messageID string) (*database.Task, error) {
		if messageID == "<parent>" {
			return &database.Task{ThreadID: "thread-abc"}, nil
		}
		return nil, nil
	}
	got := resolveThreadID("msg-2", "<parent>", "", lookup)
	if got != "thread-abc" {
		t.Fatalf("expected thread-abc, got %s", got)
	}
}

func TestResolveThreadID_ReferencesOnly_LastIDMatches(t *testing.T) {
	lookup := func(messageID string) (*database.Task, error) {
		if messageID == "<C>" {
			return &database.Task{ThreadID: "thread-c"}, nil
		}
		return nil, nil
	}
	got := resolveThreadID("msg-3", "", "<A> <B> <C>", lookup)
	if got != "thread-c" {
		t.Fatalf("expected thread-c, got %s", got)
	}
}

func TestResolveThreadID_ReferencesOnly_MiddleIDMatches(t *testing.T) {
	lookup := func(messageID string) (*database.Task, error) {
		if messageID == "<B>" {
			return &database.Task{ThreadID: "thread-b"}, nil
		}
		return nil, nil
	}
	got := resolveThreadID("msg-4", "", "<A> <B> <C>", lookup)
	if got != "thread-b" {
		t.Fatalf("expected thread-b, got %s", got)
	}
}

func TestResolveThreadID_ReferencesOnly_NoMatch_ReturnsMessageID(t *testing.T) {
	got := resolveThreadID("msg-5", "", "<X> <Y>", nilLookup)
	if got != "msg-5" {
		t.Fatalf("expected msg-5, got %s", got)
	}
}

func TestResolveThreadID_InReplyToMiss_ReferencesMatches(t *testing.T) {
	lookup := func(messageID string) (*database.Task, error) {
		if messageID == "<ref>" {
			return &database.Task{ThreadID: "thread-ref"}, nil
		}
		return nil, nil
	}
	got := resolveThreadID("msg-6", "<unknown>", "<ref>", lookup)
	if got != "thread-ref" {
		t.Fatalf("expected thread-ref, got %s", got)
	}
}

func TestResolveThreadID_LookupError_ReturnsMessageID(t *testing.T) {
	lookup := func(messageID string) (*database.Task, error) {
		return nil, errors.New("db error")
	}
	got := resolveThreadID("msg-7", "<parent>", "", lookup)
	if got != "msg-7" {
		t.Fatalf("expected msg-7, got %s", got)
	}
}

var nilLookup = func(string) (*database.Task, error) { return nil, nil }