package inference

import (
	"testing"
)

func TestProviderString(t *testing.T) {
	tests := []struct {
		provider Provider
		expected string
	}{
		{ProviderZAI, "zai"},
		{ProviderVenice, "venice"},
		{ProviderOpenRouter, "openrouter"},
	}

	for _, tt := range tests {
		t.Run(tt.expected, func(t *testing.T) {
			if got := tt.provider.String(); got != tt.expected {
				t.Errorf("Provider.String() = %q, want %q", got, tt.expected)
			}
		})
	}
}

func TestProviderInfo(t *testing.T) {
	tests := []struct {
		provider     Provider
		expectedName string
		expectedEnv  string
		expectedURL  string
	}{
		{ProviderZAI, "Z.ai", "GLM_API_KEY", "https://api.z.ai/api/coding/paas/v4"},
		{ProviderVenice, "Venice.ai", "VENICE_API_KEY", "https://api.venice.ai/api/v1"},
		{ProviderOpenRouter, "OpenRouter", "OPENROUTER_API_KEY", "https://openrouter.ai/api/v1"},
	}

	for _, tt := range tests {
		t.Run(tt.expectedName, func(t *testing.T) {
			name, env, url := tt.provider.Info()
			if name != tt.expectedName {
				t.Errorf("Provider.Info() name = %q, want %q", name, tt.expectedName)
			}
			if env != tt.expectedEnv {
				t.Errorf("Provider.Info() env = %q, want %q", env, tt.expectedEnv)
			}
			if url != tt.expectedURL {
				t.Errorf("Provider.Info() url = %q, want %q", url, tt.expectedURL)
			}
		})
	}
}

func TestFallbackChain(t *testing.T) {
	tests := []struct {
		provider         Provider
		expectedChainLen int
	}{
		{ProviderZAI, 3},        // ZAI -> Venice -> OpenRouter
		{ProviderVenice, 2},     // Venice -> OpenRouter
		{ProviderOpenRouter, 1}, // OpenRouter (no fallback)
	}

	for _, tt := range tests {
		t.Run(tt.provider.String(), func(t *testing.T) {
			chain := tt.provider.FallbackChain()
			if len(chain) != tt.expectedChainLen {
				t.Errorf("FallbackChain() length = %d, want %d", len(chain), tt.expectedChainLen)
			}
			// First element should be the provider itself
			if len(chain) > 0 && chain[0] != tt.provider {
				t.Errorf("FallbackChain()[0] = %v, want %v", chain[0], tt.provider)
			}
		})
	}
}

func TestProviderUnmarshal(t *testing.T) {
	tests := []struct {
		input       string
		expected    Provider
		expectError bool
	}{
		{"zai", ProviderZAI, false},
		{"z.ai", ProviderZAI, false},
		{"ZAI", ProviderZAI, false},
		{"venice", ProviderVenice, false},
		{"venice.ai", ProviderVenice, false},
		{"Venice", ProviderVenice, false},
		{"openrouter", ProviderOpenRouter, false},
		{"open-router", ProviderOpenRouter, false},
		{"OpenRouter", ProviderOpenRouter, false},
		{"unknown", Provider(""), true},
	}

	for _, tt := range tests {
		t.Run(tt.input, func(t *testing.T) {
			var p Provider
			err := p.UnmarshalText([]byte(tt.input))
			if tt.expectError {
				if err == nil {
					t.Error("UnmarshalText() expected error, got nil")
				}
			} else {
				if err != nil {
					t.Errorf("UnmarshalText() unexpected error: %v", err)
				}
				if p != tt.expected {
					t.Errorf("UnmarshalText() = %v, want %v", p, tt.expected)
				}
			}
		})
	}
}

func TestNewProviderSelection(t *testing.T) {
	selection := NewProviderSelection(ProviderZAI)

	if selection.Primary != ProviderZAI {
		t.Errorf("NewProviderSelection() Primary = %v, want %v", selection.Primary, ProviderZAI)
	}
	if selection.Model != "glm-5.1" {
		t.Errorf("NewProviderSelection() Model = %q, want %q", selection.Model, "glm-5.1")
	}
	if selection.MaxTokens != 16384 {
		t.Errorf("NewProviderSelection() MaxTokens = %d, want %d", selection.MaxTokens, 16384)
	}
	// Verify fallback chain
	if len(selection.FallbackChain) != 3 {
		t.Errorf("NewProviderSelection() FallbackChain length = %d, want %d", len(selection.FallbackChain), 3)
	}
}

func TestProviderSelectionValidate(t *testing.T) {
	tests := []struct {
		name        string
		selection   *ProviderSelection
		expectError bool
	}{
		{
			name: "valid selection",
			selection: &ProviderSelection{
				Primary:       ProviderZAI,
				FallbackChain: []Provider{ProviderZAI, ProviderVenice, ProviderOpenRouter},
				Model:         "glm-5.1",
				MaxTokens:     16384,
			},
			expectError: false,
		},
		{
			name: "zero max_tokens",
			selection: &ProviderSelection{
				Primary:   ProviderZAI,
				Model:     "glm-5.1",
				MaxTokens: 0,
			},
			expectError: true,
		},
		{
			name: "negative max_tokens",
			selection: &ProviderSelection{
				Primary:   ProviderZAI,
				Model:     "glm-5.1",
				MaxTokens: -100,
			},
			expectError: true,
		},
		{
			name: "excessive max_tokens",
			selection: &ProviderSelection{
				Primary:   ProviderZAI,
				Model:     "glm-5.1",
				MaxTokens: 200000,
			},
			expectError: true,
		},
		{
			name: "empty model",
			selection: &ProviderSelection{
				Primary:   ProviderZAI,
				Model:     "",
				MaxTokens: 16384,
			},
			expectError: true,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			err := tt.selection.Validate()
			if tt.expectError {
				if err == nil {
					t.Error("Validate() expected error, got nil")
				}
			} else {
				if err != nil {
					t.Errorf("Validate() unexpected error: %v", err)
				}
			}
		})
	}
}

func TestAPIKeyEnvVars(t *testing.T) {
	tests := []struct {
		name          string
		providers     []Provider
		expectedCount int
	}{
		{
			name:          "single provider",
			providers:     []Provider{ProviderZAI},
			expectedCount: 1,
		},
		{
			name:          "ZAI fallback chain",
			providers:     []Provider{ProviderZAI, ProviderVenice, ProviderOpenRouter},
			expectedCount: 3,
		},
		{
			name:          "Venice only",
			providers:     []Provider{ProviderVenice},
			expectedCount: 1,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			vars := APIKeyEnvVars(tt.providers...)
			if len(vars) != tt.expectedCount {
				t.Errorf("APIKeyEnvVars() length = %d, want %d", len(vars), tt.expectedCount)
			}
		})
	}
}

func TestDefaultGLMConfig(t *testing.T) {
	config := DefaultGLMConfig()

	if config.Provider != ProviderZAI {
		t.Errorf("DefaultGLMConfig() Provider = %v, want %v", config.Provider, ProviderZAI)
	}
	if config.Model != "glm-5.1" {
		t.Errorf("DefaultGLMConfig() Model = %q, want %q", config.Model, "glm-5.1")
	}
	if config.MaxTokens != 16384 {
		t.Errorf("DefaultGLMConfig() MaxTokens = %d, want %d", config.MaxTokens, 16384)
	}
}

func TestGetProviderOptions(t *testing.T) {
	options := GetProviderOptions()

	if len(options) != 3 {
		t.Errorf("GetProviderOptions() length = %d, want %d", len(options), 3)
	}

	// Check Z.ai is marked as recommended
	foundZAI := false
	for _, opt := range options {
		if opt.Provider == ProviderZAI {
			foundZAI = true
			if !opt.Recommended {
				t.Error("Z.ai should be marked as recommended")
			}
		}
	}
	if !foundZAI {
		t.Error("Z.ai provider not found in options")
	}
}

func TestFormatProviderList(t *testing.T) {
	list := FormatProviderList()

	// Check that it contains expected provider names
	expectedStrings := []string{"Z.ai", "Venice.ai", "OpenRouter", "recommended"}
	for _, s := range expectedStrings {
		if !contains(list, s) {
			t.Errorf("FormatProviderList() missing expected string %q", s)
		}
	}
}

func contains(s, substr string) bool {
	for i := 0; i <= len(s)-len(substr); i++ {
		if s[i:i+len(substr)] == substr {
			return true
		}
	}
	return false
}