package service

import (
	"encoding/base64"
	"net"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"
)

func TestNormalizeOutboundHeadersAllowsCustomUserAgent(t *testing.T) {
	headers, err := NormalizeOutboundHeaders([]OutboundHeader{{Name: "user-agent", Value: "Custom Gateway/2.0"}, {Name: "X-Gateway-Tenant", Value: "tenant-a"}})
	if err != nil {
		t.Fatal(err)
	}
	request, _ := http.NewRequest(http.MethodGet, "https://example.com", nil)
	ApplyOutboundHeaders(request, headers)
	ApplyDefaultOutboundHeaders(request)
	if got := request.Header.Get("User-Agent"); got != "Custom Gateway/2.0" {
		t.Fatalf("User-Agent = %q", got)
	}
	if got := request.Header.Get("X-Gateway-Tenant"); got != "tenant-a" {
		t.Fatalf("X-Gateway-Tenant = %q", got)
	}
}

func TestNormalizeOutboundHeadersRejectsUnsafeAndDuplicateValues(t *testing.T) {
	tests := [][]OutboundHeader{
		{{Name: "Authorization", Value: "Bearer attacker"}},
		{{Name: "X-Test", Value: "safe\r\ninjected: true"}},
		{{Name: "X-Test", Value: "one"}, {Name: "x-test", Value: "two"}},
	}
	for _, headers := range tests {
		if _, err := NormalizeOutboundHeaders(headers); err == nil {
			t.Fatalf("NormalizeOutboundHeaders(%#v) should fail", headers)
		}
	}
}

func TestDecodeRelayOutboundHeaders(t *testing.T) {
	raw := base64.StdEncoding.EncodeToString([]byte(`[{"name":"User-Agent","value":"Relay Agent"}]`))
	headers, err := DecodeRelayOutboundHeaders(raw)
	if err != nil {
		t.Fatal(err)
	}
	if len(headers) != 1 || headers[0].Name != "User-Agent" || headers[0].Value != "Relay Agent" {
		t.Fatalf("DecodeRelayOutboundHeaders() = %#v", headers)
	}
}

func TestApplyDefaultOutboundHeaders(t *testing.T) {
	request, err := http.NewRequest(http.MethodGet, "https://example.com", nil)
	if err != nil {
		t.Fatal(err)
	}
	ApplyDefaultOutboundHeaders(request)
	if got := request.Header.Get("User-Agent"); got != DefaultOutboundUserAgent {
		t.Fatalf("User-Agent = %q, want %q", got, DefaultOutboundUserAgent)
	}

	request.Header.Set("User-Agent", "custom-agent")
	ApplyDefaultOutboundHeaders(request)
	if got := request.Header.Get("User-Agent"); got != "custom-agent" {
		t.Fatalf("custom User-Agent = %q", got)
	}
}

func TestValidateOutboundURLRejectsPrivateHosts(t *testing.T) {
	t.Setenv("CANVAS_ALLOW_PRIVATE_UPSTREAMS", "false")
	t.Setenv("CANVAS_ALLOWED_PRIVATE_UPSTREAM_HOSTS", "")
	for _, rawURL := range []string{"http://127.0.0.1:8080", "http://localhost:8080", "http://169.254.169.254/latest/meta-data"} {
		if _, err := ValidateOutboundURL(rawURL); err == nil {
			t.Fatalf("ValidateOutboundURL(%q) should fail", rawURL)
		}
	}
}

func TestValidateOutboundURLAllowsExplicitPrivateUpstreamOverride(t *testing.T) {
	t.Setenv("CANVAS_ALLOW_PRIVATE_UPSTREAMS", "true")
	t.Setenv("CANVAS_ALLOWED_PRIVATE_UPSTREAM_HOSTS", "")
	if _, err := ValidateOutboundURL("http://127.0.0.1:8080"); err != nil {
		t.Fatalf("ValidateOutboundURL() error = %v", err)
	}
}

func TestValidateOutboundURLAllowsOnlyNamedPrivateUpstream(t *testing.T) {
	t.Setenv("CANVAS_ALLOW_PRIVATE_UPSTREAMS", "false")
	t.Setenv("CANVAS_ALLOWED_PRIVATE_UPSTREAM_HOSTS", "127.0.0.1")
	if _, err := ValidateOutboundURL("http://127.0.0.1:8080"); err != nil {
		t.Fatalf("ValidateOutboundURL() error = %v", err)
	}
	if _, err := ValidateOutboundURL("http://127.0.0.2:8080"); err == nil {
		t.Fatal("ValidateOutboundURL() should reject an unlisted private host")
	}
}

func TestAllowedPrivateUpstreamHostUsesExactCaseInsensitiveMatch(t *testing.T) {
	t.Setenv("CANVAS_ALLOWED_PRIVATE_UPSTREAM_HOSTS", " API.EXAMPLE.COM.,trusted.internal ")
	if !allowedPrivateUpstreamHost("api.example.com") {
		t.Fatal("allowedPrivateUpstreamHost() should allow exact normalized hostname")
	}
	if allowedPrivateUpstreamHost("api.example.com.evil.test") {
		t.Fatal("allowedPrivateUpstreamHost() should reject hostname suffix confusion")
	}
}

func TestValidateCustomRelayURLUsesHTTPSAndExactPrivateAllowlist(t *testing.T) {
	t.Setenv("CANVAS_ALLOW_PRIVATE_UPSTREAMS", "true")
	t.Setenv("CANVAS_ALLOWED_PRIVATE_UPSTREAM_HOSTS", "")
	if _, err := ValidateCustomRelayURL("http://127.0.0.1:8080/v1/models"); err == nil {
		t.Fatal("ValidateCustomRelayURL() should reject HTTP")
	}
	if _, err := ValidateCustomRelayURL("https://127.0.0.1:8080/v1/models"); err == nil {
		t.Fatal("ValidateCustomRelayURL() should ignore the global private upstream override")
	}
	t.Setenv("CANVAS_ALLOWED_PRIVATE_UPSTREAM_HOSTS", "127.0.0.1")
	if _, err := ValidateCustomRelayURL("https://127.0.0.1:8080/v1/models"); err != nil {
		t.Fatalf("ValidateCustomRelayURL() error = %v", err)
	}
}

func TestValidateCustomRelayURLRejectsCredentialsAndFragment(t *testing.T) {
	t.Setenv("CANVAS_ALLOWED_PRIVATE_UPSTREAM_HOSTS", "127.0.0.1")
	for _, rawURL := range []string{
		"https://user:pass@127.0.0.1/v1/models",
		"https://127.0.0.1/v1/models#secret",
	} {
		if _, err := ValidateCustomRelayURL(rawURL); err == nil {
			t.Fatalf("ValidateCustomRelayURL(%q) should fail", rawURL)
		}
	}
}

func TestBlockedCustomRelayIPRejectsCarrierGradeNATAndReservedRanges(t *testing.T) {
	for _, value := range []string{"100.100.100.200", "192.0.2.10", "198.18.0.1", "2001:db8::1"} {
		if !blockedCustomRelayIP(net.ParseIP(value)) {
			t.Fatalf("blockedCustomRelayIP(%q) = false", value)
		}
	}
	if blockedCustomRelayIP(net.ParseIP("8.8.8.8")) {
		t.Fatal("blockedCustomRelayIP() rejected a public address")
	}
}

func TestCustomRelayHTTPClientDoesNotFollowRedirects(t *testing.T) {
	redirected := false
	destination := httptest.NewTLSServer(http.HandlerFunc(func(http.ResponseWriter, *http.Request) {
		redirected = true
	}))
	defer destination.Close()
	source := httptest.NewTLSServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.Header().Set("Location", destination.URL)
		w.WriteHeader(http.StatusFound)
	}))
	defer source.Close()

	client := CustomRelayHTTPClient(time.Second)
	client.Transport = source.Client().Transport
	if _, err := client.Get(source.URL); err == nil {
		t.Fatal("CustomRelayHTTPClient() should reject redirects")
	}
	if redirected {
		t.Fatal("redirect destination should not receive the request")
	}
}