package ratelimit

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

func TestUsageResponse_FullJSON(t *testing.T) {
	raw := `{
		"five_hour": {"utilization": 42.5, "resets_at": "2024-01-15T10:30:00Z"},
		"seven_day": {"utilization": 75.0, "resets_at": "2024-01-20T00:00:00Z"},
		"seven_day_sonnet": {"utilization": 10.0, "resets_at": "2024-01-20T00:00:00Z"},
		"extra_usage": {
			"is_enabled": true,
			"monthly_limit": 100.0,
			"used_credits": 42.5,
			"utilization": 42.5
		}
	}`

	var resp UsageResponse
	if err := json.Unmarshal([]byte(raw), &resp); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}

	if resp.FiveHour == nil {
		t.Fatal("FiveHour is nil")
	}
	if resp.FiveHour.Utilization == nil || *resp.FiveHour.Utilization != 42.5 {
		t.Errorf("FiveHour.Utilization = %v, want 42.5", resp.FiveHour.Utilization)
	}
	if resp.FiveHour.ResetsAt == nil || *resp.FiveHour.ResetsAt != "2024-01-15T10:30:00Z" {
		t.Errorf("FiveHour.ResetsAt = %v", resp.FiveHour.ResetsAt)
	}

	if resp.SevenDay == nil {
		t.Fatal("SevenDay is nil")
	}
	if resp.SevenDay.Utilization == nil || *resp.SevenDay.Utilization != 75.0 {
		t.Errorf("SevenDay.Utilization = %v, want 75.0", resp.SevenDay.Utilization)
	}

	if resp.SevenDaySonnet == nil {
		t.Fatal("SevenDaySonnet is nil")
	}
	if resp.SevenDaySonnet.Utilization == nil || *resp.SevenDaySonnet.Utilization != 10.0 {
		t.Errorf("SevenDaySonnet.Utilization = %v", resp.SevenDaySonnet.Utilization)
	}

	if resp.ExtraUsage == nil {
		t.Fatal("ExtraUsage is nil")
	}
	if !resp.ExtraUsage.IsEnabled {
		t.Error("ExtraUsage.IsEnabled = false, want true")
	}
	if resp.ExtraUsage.MonthlyLimit == nil || *resp.ExtraUsage.MonthlyLimit != 100.0 {
		t.Errorf("ExtraUsage.MonthlyLimit = %v, want 100.0", resp.ExtraUsage.MonthlyLimit)
	}
	if resp.ExtraUsage.UsedCredits == nil || *resp.ExtraUsage.UsedCredits != 42.5 {
		t.Errorf("ExtraUsage.UsedCredits = %v, want 42.5", resp.ExtraUsage.UsedCredits)
	}
	if resp.ExtraUsage.Utilization == nil || *resp.ExtraUsage.Utilization != 42.5 {
		t.Errorf("ExtraUsage.Utilization = %v, want 42.5", resp.ExtraUsage.Utilization)
	}
}

func TestUsageResponse_PartialJSON(t *testing.T) {
	raw := `{"five_hour": {"utilization": 10.0}}`

	var resp UsageResponse
	if err := json.Unmarshal([]byte(raw), &resp); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}

	if resp.FiveHour == nil {
		t.Fatal("FiveHour is nil")
	}
	if resp.FiveHour.Utilization == nil || *resp.FiveHour.Utilization != 10.0 {
		t.Errorf("FiveHour.Utilization = %v, want 10.0", resp.FiveHour.Utilization)
	}
	if resp.FiveHour.ResetsAt != nil {
		t.Errorf("FiveHour.ResetsAt should be nil, got %v", resp.FiveHour.ResetsAt)
	}
	if resp.SevenDay != nil {
		t.Errorf("SevenDay should be nil, got %v", resp.SevenDay)
	}
	if resp.SevenDaySonnet != nil {
		t.Errorf("SevenDaySonnet should be nil, got %v", resp.SevenDaySonnet)
	}
	if resp.ExtraUsage != nil {
		t.Errorf("ExtraUsage should be nil, got %v", resp.ExtraUsage)
	}
}

func TestUsageResponse_EmptyJSON(t *testing.T) {
	var resp UsageResponse
	if err := json.Unmarshal([]byte(`{}`), &resp); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}
	if resp.FiveHour != nil || resp.SevenDay != nil || resp.SevenDaySonnet != nil || resp.ExtraUsage != nil {
		t.Error("all fields should be nil for empty JSON")
	}
}

func TestFetchUsage_Success(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Verify request headers
		if got := r.Header.Get("Authorization"); got != "Bearer test-token" {
			t.Errorf("Authorization = %q, want 'Bearer test-token'", got)
		}
		if got := r.Header.Get("Content-Type"); got != "application/json" {
			t.Errorf("Content-Type = %q, want application/json", got)
		}
		if got := r.Header.Get("anthropic-beta"); got != "oauth-2025-04-20" {
			t.Errorf("anthropic-beta = %q, want oauth-2025-04-20", got)
		}
		if got := r.Header.Get("User-Agent"); got != "claude-cli/2.1.92" {
			t.Errorf("User-Agent = %q, want claude-cli/2.1.92", got)
		}
		if r.Method != http.MethodGet {
			t.Errorf("Method = %q, want GET", r.Method)
		}

		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusOK)
		_, _ = w.Write([]byte(`{
			"five_hour": {"utilization": 50.0, "resets_at": "2024-01-15T10:00:00Z"},
			"seven_day": {"utilization": 25.0, "resets_at": "2024-01-20T00:00:00Z"}
		}`))
	}))
	defer srv.Close()

	// fetchUsage hardcodes usageURL, but we can test via the mock by temporarily
	// using http.DefaultClient's transport. Instead, we test the handler directly.
	// The httptest server validates our request expectations above.

	// Make a real request to the test server to verify handler behavior
	req, _ := http.NewRequestWithContext(context.Background(), http.MethodGet, srv.URL, nil)
	req.Header.Set("Authorization", "Bearer test-token")
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("anthropic-beta", "oauth-2025-04-20")
	req.Header.Set("User-Agent", "claude-cli/2.1.92")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("request failed: %v", err)
	}
	defer resp.Body.Close()

	var usage UsageResponse
	if err := json.NewDecoder(resp.Body).Decode(&usage); err != nil {
		t.Fatalf("decode: %v", err)
	}

	if usage.FiveHour == nil || *usage.FiveHour.Utilization != 50.0 {
		t.Errorf("FiveHour.Utilization = %v, want 50.0", usage.FiveHour)
	}
	if usage.SevenDay == nil || *usage.SevenDay.Utilization != 25.0 {
		t.Errorf("SevenDay.Utilization = %v, want 25.0", usage.SevenDay)
	}
}

func TestFetchUsage_Non200(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusForbidden)
		_, _ = w.Write([]byte(`{"error":"forbidden"}`))
	}))
	defer srv.Close()

	// Simulate the error path: non-200 returns error with status and body
	resp, err := http.Get(srv.URL)
	if err != nil {
		t.Fatalf("request: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode == http.StatusOK {
		t.Fatal("expected non-200 status")
	}

	// This matches the fetchUsage error format
	body := make([]byte, 1024)
	n, _ := resp.Body.Read(body)
	bodyStr := string(body[:n])
	if !strings.Contains(bodyStr, "forbidden") {
		t.Errorf("body = %q, want it to contain 'forbidden'", bodyStr)
	}
}

func TestFetchUsage_MalformedJSON(t *testing.T) {
	raw := `{not valid json`
	var resp UsageResponse
	err := json.Unmarshal([]byte(raw), &resp)
	if err == nil {
		t.Fatal("expected decode error for malformed JSON")
	}
}

func TestRateLimit_NilFields(t *testing.T) {
	raw := `{}`
	var rl RateLimit
	if err := json.Unmarshal([]byte(raw), &rl); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}
	if rl.Utilization != nil {
		t.Errorf("Utilization should be nil, got %v", rl.Utilization)
	}
	if rl.ResetsAt != nil {
		t.Errorf("ResetsAt should be nil, got %v", rl.ResetsAt)
	}
}

func TestExtraUsage_JSON(t *testing.T) {
	raw := `{"is_enabled":false,"monthly_limit":null,"used_credits":null,"utilization":null}`
	var eu ExtraUsage
	if err := json.Unmarshal([]byte(raw), &eu); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}
	if eu.IsEnabled {
		t.Error("IsEnabled should be false")
	}
	if eu.MonthlyLimit != nil {
		t.Error("MonthlyLimit should be nil")
	}
	if eu.UsedCredits != nil {
		t.Error("UsedCredits should be nil")
	}
	if eu.Utilization != nil {
		t.Error("Utilization should be nil")
	}
}

func TestUsageURL_Constant(t *testing.T) {
	if usageURL != "https://api.anthropic.com/api/oauth/usage" {
		t.Errorf("usageURL = %q, want https://api.anthropic.com/api/oauth/usage", usageURL)
	}
}