package agent

import (
	"encoding/json"
	"os"
	"testing"

	"ollie/backend"
)

type mockBackendForCompact struct {
	name  string
	model string
}

func (b *mockBackendForCompact) Name() string  { return b.name }
func (b *mockBackendForCompact) Model() string { return b.model }

func TestResolveCompactionModel_ConfigWins(t *testing.T) {
	b := &mockBackendForCompact{name: "anthropic", model: "claude-sonnet-4-5"}
	got := resolveCompactionModel("my-custom-model", b)
	if got != "my-custom-model" {
		t.Errorf("got %q; want my-custom-model", got)
	}
}

func TestResolveCompactionModel_EnvOverridesDefault(t *testing.T) {
	t.Setenv("OLLIE_COMPACTION_MODEL", "env-model")
	b := &mockBackendForCompact{name: "anthropic", model: "claude-sonnet-4-5"}
	got := resolveCompactionModel("", b)
	if got != "env-model" {
		t.Errorf("got %q; want env-model", got)
	}
}

func TestResolveCompactionModel_BackendDefault(t *testing.T) {
	os.Unsetenv("OLLIE_COMPACTION_MODEL")
	tests := []struct {
		backend string
		want    string
	}{
		{"anthropic", "claude-3-5-haiku-latest"},
		{"openai", "gpt-4o-mini"},
		{"openrouter", "deepseek-v4-flash"},
		{"gemini", "gemini-2.0-flash"},
		{"ollama", ""},
	}
	for _, tt := range tests {
		b := &mockBackendForCompact{name: tt.backend}
		got := resolveCompactionModel("", b)
		if got != tt.want {
			t.Errorf("backend=%s: got %q; want %q", tt.backend, got, tt.want)
		}
	}
}

func TestBuildCompactedHistory_OrphanedToolMessage(t *testing.T) {
	// Simulate a history where the hot zone boundary (total - hotTailSize)
	// lands on a tool message whose preceding assistant+tool_calls is outside
	// the hot zone. Without the fix, this produces an orphaned tool message
	// that causes OpenAI 400 errors.
	var msgs []backend.Message

	// Pad with enough messages so the boundary falls on the tool message.
	// We need total - hotTailSize to land on the tool result.
	// hotTailSize = 8, so we need the tool msg at index total-8.
	// Build: 10 user/assistant pairs (20 msgs), then assistant+tool_calls, tool result, then 7 more messages.
	for i := range 10 {
		msgs = append(msgs,
			backend.Message{Role: "user", Content: "q" + string(rune('0'+i))},
			backend.Message{Role: "assistant", Content: "a" + string(rune('0'+i))},
		)
	}
	// assistant with tool_calls at index 20
	msgs = append(msgs, backend.Message{
		Role:      "assistant",
		ToolCalls: []backend.ToolCall{{ID: "call_orphan", Name: "test_tool", Arguments: json.RawMessage(`{}`)}},
	})
	// tool result at index 21 — this is where hotStart would land without the fix
	msgs = append(msgs, backend.Message{
		Role:       "tool",
		Content:    "tool output",
		ToolCallID: "call_orphan",
	})
	// 7 more messages to fill the rest of the hot zone (indices 22-28)
	for i := range 3 {
		msgs = append(msgs,
			backend.Message{Role: "user", Content: "follow " + string(rune('0'+i))},
			backend.Message{Role: "assistant", Content: "reply " + string(rune('0'+i))},
		)
	}
	msgs = append(msgs, backend.Message{Role: "user", Content: "final"})
	// total = 29, hotStart = 29 - 8 = 21 (the tool message)

	ts := TaskState{Objective: "test"}
	result := buildCompactedHistory(ts, msgs)

	// Verify no tool message appears without a preceding assistant+tool_calls.
	for i, m := range result {
		if m.Role == "tool" {
			if i == 0 {
				t.Fatalf("result[0] is a tool message — no preceding assistant")
			}
			prev := result[i-1]
			if prev.Role != "assistant" && prev.Role != "tool" {
				t.Fatalf("result[%d] is tool but result[%d] is %q (want assistant or tool)", i, i-1, prev.Role)
			}
			if prev.Role == "assistant" && len(prev.ToolCalls) == 0 {
				t.Fatalf("result[%d] is tool but preceding assistant has no tool_calls", i)
			}
		}
	}
}