package config

import (
	"fmt"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"testing"
	"time"

	"go.yaml.in/yaml/v4"

	"proxy-pool/internal/domain/authorization"
	"proxy-pool/internal/domain/clientpolicy"
)

const validConfig = `
version: 1
security:
  requireProtectionOnPublicListen: true
gateway:
  enabled: true
  listen: 127.0.0.1:8080
  auth:
    mode: none
distribution:
  enabled: true
  listen: 127.0.0.1:8081
  auth:
    mode: none
  extraction:
    fulfillment: partial
    maxCountPerRequest: 20
    minRemainingTTL: 30s
    maxHealthCheckAge: 15s
    reserveForGateway: 5
routing:
  - name: extract
    enabled: true
    purpose: extract
    upstreams: [provider-a, provider-b]
    strategy:
      type: sequential
      switchAfterEmptyFetch: 5
      endBehavior: stayLast
    onUnavailable:
      action: reject
upstreams:
  provider-a: &valid-upstream
    enabled: true
    exposure: [gateway, extract]
    provider:
      billingMode: fetch
      protocols: [http]
    api:
      url: https://provider.example/proxies
      method: GET
      template: '{{.}}'
      auth:
        type: none
    proxyAuth:
      type: response
    pool:
      maxSize: 100
    capacity:
      maxConcurrencyPerProxy: 10
    refill:
      reconcileInterval: 1s
      minimumAvailableSlots: 200
      targetAvailableSlots: 500
    lifecycle:
      ttl: 120s
      allocationSafetyMargin: 10s
    fetch:
      estimatedIPsPerCall: 20
      requestInterval: 1s
      timeout: 3s
      maxAttempts: 5
      maxInFlight: 1
      maxTotal: 1000
    check:
      interval: 30s
      jitter: 20
      maxInFlight: 100
      timeout: 2s
      maxAttempts: 2
      maxConsecutiveFailures: 3
      urls: [http://connect.rom.miui.com/generate_204]
  provider-b: *valid-upstream
`

func TestLoadStrictValidConfiguration(t *testing.T) {
	cfg, err := Load(strings.NewReader(validConfig))
	if err != nil {
		t.Fatalf("Load(): %v", err)
	}
	provider := cfg.Upstreams["provider-a"]
	if cfg.Version != 1 || provider.Pool.MaxSize != 100 || provider.Fetch.EstimatedIPsPerCall != 20 ||
		provider.Refill.ReconcileInterval.Value() != time.Second || provider.Refill.MinimumAvailableSlots != 200 ||
		provider.Refill.TargetAvailableSlots != 500 {
		t.Fatalf("unexpected config: %+v", cfg)
	}
}

func TestLoadPreservesOmittedAndExplicitDestinationPolicyBooleans(t *testing.T) {
	source := strings.Replace(validConfig,
		"  auth:\n    mode: none\n",
		"  auth:\n    mode: none\n  destinationPolicy:\n    denyLoopback: false\n",
		1,
	)
	cfg, err := Load(strings.NewReader(source))
	if err != nil {
		t.Fatalf("Load() error = %v", err)
	}
	policy := cfg.Gateway.DestinationPolicy
	if policy.DenyLoopback == nil || *policy.DenyLoopback {
		t.Fatalf("denyLoopback = %v, want explicit false", policy.DenyLoopback)
	}
	if policy.DenyPrivateNetworks != nil || policy.DenyLinkLocal != nil {
		t.Fatalf("omitted policy fields = (%v, %v), want nil", policy.DenyPrivateNetworks, policy.DenyLinkLocal)
	}
	redacted := cfg.Redacted()
	*redacted.Gateway.DestinationPolicy.DenyLoopback = true
	if *cfg.Gateway.DestinationPolicy.DenyLoopback {
		t.Fatal("Redacted() destination policy aliases source configuration")
	}
}

func TestLoadRejectsUnknownFields(t *testing.T) {
	_, err := Load(strings.NewReader(validConfig + "unknownField: true\n"))
	if err == nil || !strings.Contains(err.Error(), "unknownField") {
		t.Fatalf("Load() error = %v, want unknown field error", err)
	}
}

func TestValidateRejectsUnprotectedPublicListener(t *testing.T) {
	cfg, err := Load(strings.NewReader(strings.Replace(validConfig,
		"listen: 127.0.0.1:8080", "listen: 0.0.0.0:8080", 1)))
	if err == nil || !strings.Contains(err.Error(), "gateway") || !strings.Contains(err.Error(), "public") {
		t.Fatalf("Load() error = %v, want unprotected public listener error", err)
	}
	if cfg != nil {
		t.Fatal("invalid config must not be returned")
	}
}

func TestValidateRejectsMissingUpstreamReference(t *testing.T) {
	broken := strings.Replace(validConfig, "upstreams: [provider-a, provider-b]", "upstreams: [provider-a, missing]", 1)
	_, err := Load(strings.NewReader(broken))
	if err == nil || !strings.Contains(err.Error(), "missing") {
		t.Fatalf("Load() error = %v, want missing upstream error", err)
	}
}

func TestValidateSeparatesPoolAndFetchLimits(t *testing.T) {
	broken := strings.Replace(validConfig, "maxTotal: 1000", "maxTotal: 50", 1)
	_, err := Load(strings.NewReader(broken))
	if err == nil || !strings.Contains(err.Error(), "maxTotal") {
		t.Fatalf("Load() error = %v, want maxTotal validation error", err)
	}
}

func TestShippedConfigurationsAreValid(t *testing.T) {
	paths, err := filepath.Glob(filepath.Join("..", "..", "examples", "config", "*.yaml"))
	if err != nil {
		t.Fatalf("Glob(): %v", err)
	}
	paths = append(paths, filepath.Join("..", "..", "configs", "proxy-pool.yaml"))
	if len(paths) != 21 {
		t.Fatalf("configuration count = %d, want 21", len(paths))
	}

	for _, path := range paths {
		path := path
		t.Run(filepath.Base(path), func(t *testing.T) {
			file, err := os.Open(path)
			if err != nil {
				t.Fatalf("Open(): %v", err)
			}
			defer file.Close()
			if _, err := Load(file); err != nil {
				t.Fatalf("Load(): %v", err)
			}
		})
	}
}

func TestShippedDeploymentConfigurationsResolveEnvironment(t *testing.T) {
	resolver := fixtureResolver{environment: map[string]string{
		"PROXY_POOL_GATEWAY_USERNAME": "resolved-gateway-user",
		"PROXY_POOL_GATEWAY_PASSWORD": "resolved-gateway-password",
		"PROXY_POOL_EXTRACT_TOKEN":    "resolved-extract-token",
		"PROXY_POOL_ADMIN_TOKEN":      "resolved-admin-token",
		"PROXY_POOL_POSTGRES_URL":     "postgres://resolved",
		"PROXY_POOL_REDIS_URL":        "redis://resolved",
		"PROVIDER_A_TOKEN":            "resolved-provider-a-token",
		"PROVIDER_B_TOKEN":            "resolved-provider-b-token",
	}}
	tests := []struct {
		name            string
		path            string
		configMap       bool
		wantGatewayUser string
		wantPostgresURL string
		wantRedisURL    string
	}{
		{
			name:            "local",
			path:            filepath.Join("..", "..", "deploy", "config", "local.yaml"),
			wantGatewayUser: "local-gateway",
			wantPostgresURL: "postgres://proxy_pool:local-only-change-me@postgres:5432/proxy_pool?sslmode=disable",
			wantRedisURL:    "redis://redis:6379/0",
		},
		{
			name:            "kubernetes",
			path:            filepath.Join("..", "..", "deploy", "kubernetes", "base", "configmap.yaml"),
			configMap:       true,
			wantGatewayUser: "resolved-gateway-user",
			wantPostgresURL: "postgres://resolved",
			wantRedisURL:    "redis://resolved",
		},
	}
	for _, test := range tests {
		test := test
		t.Run(test.name, func(t *testing.T) {
			content, err := os.ReadFile(test.path)
			if err != nil {
				t.Fatalf("ReadFile(): %v", err)
			}
			configuration := string(content)
			if test.configMap {
				var manifest struct {
					Data map[string]string `yaml:"data"`
				}
				if err := yaml.Unmarshal(content, &manifest); err != nil {
					t.Fatalf("Unmarshal(): %v", err)
				}
				configuration = manifest.Data["config.yaml"]
			}
			cfg, err := LoadResolved(strings.NewReader(configuration), resolver)
			if err != nil {
				t.Fatalf("LoadResolved(): %v", err)
			}
			if cfg.Gateway.Auth.Username != test.wantGatewayUser ||
				cfg.Gateway.Auth.Password != "resolved-gateway-password" ||
				cfg.Distribution.Auth.Token != "resolved-extract-token" ||
				cfg.Admin.Auth.Token != "resolved-admin-token" ||
				cfg.Storage.PostgresURL != test.wantPostgresURL ||
				cfg.Storage.RedisURL != test.wantRedisURL ||
				cfg.Upstreams["provider-a"].API.Auth.Value != "resolved-provider-a-token" ||
				cfg.Upstreams["provider-b"].API.Auth.Value != "resolved-provider-b-token" {
				t.Fatalf("deployment values were not resolved: %+v", cfg.Redacted())
			}
		})
	}
}

func TestLoadResolvedExpandsEnvironmentWithoutChangingTemplateVariables(t *testing.T) {
	configured := strings.Replace(validConfig, `      auth:
        type: none`, `      auth:
        type: basic
        username: "${PROVIDER_USER}"
        password: "${PROVIDER_PASSWORD}"`, 1)
	configured = strings.Replace(configured, "template: '{{.}}'", "template: '{{$x := .}}{{$x}}'", 1)
	resolver := fixtureResolver{environment: map[string]string{
		"PROVIDER_USER":     "alice",
		"PROVIDER_PASSWORD": "secret",
	}}

	cfg, err := LoadResolved(strings.NewReader(configured), resolver)
	if err != nil {
		t.Fatalf("LoadResolved(): %v", err)
	}
	auth := cfg.Upstreams["provider-a"].API.Auth
	if auth.Username != "alice" || auth.Password != "secret" {
		t.Fatalf("resolved auth = %+v", auth)
	}
	if got := cfg.Upstreams["provider-a"].API.Template; got != "{{$x := .}}{{$x}}" {
		t.Fatalf("template = %q, want template variable unchanged", got)
	}
}

func TestLoadResolvedReadsSecretFileAndClearsReference(t *testing.T) {
	configured := strings.Replace(validConfig, `      auth:
        type: none`, `      auth:
        type: basic
        username: alice
        passwordFile: /run/secrets/provider-password`, 1)
	resolver := fixtureResolver{files: map[string]string{
		"/run/secrets/provider-password": "file-secret\r\n",
	}}

	cfg, err := LoadResolved(strings.NewReader(configured), resolver)
	if err != nil {
		t.Fatalf("LoadResolved(): %v", err)
	}
	auth := cfg.Upstreams["provider-a"].API.Auth
	if auth.Password != "file-secret" || auth.PasswordFile != "" {
		t.Fatalf("resolved auth = %+v", auth)
	}
}

func TestLoadRejectsMultipleYAMLDocuments(t *testing.T) {
	_, err := Load(strings.NewReader(validConfig + "\n---\nversion: 1\n"))
	if err == nil || !strings.Contains(err.Error(), "multiple YAML documents") {
		t.Fatalf("Load() error = %v, want multiple document error", err)
	}
}

func TestValidateRejectsUnsupportedListenerAuthMode(t *testing.T) {
	broken := strings.Replace(validConfig, "mode: none", "mode: custom", 1)
	_, err := Load(strings.NewReader(broken))
	if err == nil || !strings.Contains(err.Error(), "auth.mode") {
		t.Fatalf("Load() error = %v, want auth.mode error", err)
	}
}

func TestValidateAcceptsBearerListenerAuthentication(t *testing.T) {
	cfg := mustLoadValidConfig(t)
	cfg.Distribution.Auth = Auth{Mode: "bearer", Token: "resolved-token"}
	cfg.Distribution.ClientIdentification.Mode = "authenticatedClient"
	if err := Validate(cfg); err != nil {
		t.Fatalf("Validate(bearer) error = %v", err)
	}

	cfg.Distribution.Auth = Auth{Mode: "any", Methods: []AuthMethod{{Mode: "bearer", Value: "method-token"}}}
	if err := Validate(cfg); err != nil {
		t.Fatalf("Validate(any bearer) error = %v", err)
	}
}

func TestValidateListenerPermissionConfiguration(t *testing.T) {
	t.Parallel()
	cfg := mustLoadValidConfig(t)
	cfg.Admin.Enabled = true
	cfg.Admin.Listen = "127.0.0.1:8082"
	cfg.Admin.Auth = Auth{
		Mode:        "bearer",
		Token:       "admin-token",
		Permissions: []string{authorization.AdminRead},
	}
	if err := Validate(cfg); err != nil {
		t.Fatalf("Validate(admin read permission) error = %v", err)
	}

	cfg.Admin.Auth.Permissions = []string{"unknown"}
	if err := Validate(cfg); err == nil || !strings.Contains(err.Error(), "permissions") {
		t.Fatalf("Validate(unknown permission) error = %v", err)
	}

	cfg.Admin.Auth = Auth{
		Mode:        "any",
		Permissions: []string{authorization.AdminRead},
		Methods: []AuthMethod{{
			Mode: "bearer", Value: "read-token", Permissions: []string{authorization.AdminRead},
		}},
	}
	if err := Validate(cfg); err == nil || !strings.Contains(err.Error(), "auth.permissions") {
		t.Fatalf("Validate(any top-level permission) error = %v", err)
	}

	cfg.Admin.Auth.Permissions = nil
	if err := Validate(cfg); err != nil {
		t.Fatalf("Validate(any method permission) error = %v", err)
	}
}

func TestValidateDistributionCredentialClientPolicy(t *testing.T) {
	t.Parallel()

	cfg, err := Load(strings.NewReader(validConfig))
	if err != nil {
		t.Fatalf("Load() error = %v", err)
	}
	cfg.Distribution.Auth = Auth{
		Mode: "bearer", Token: "distribution-token",
		ClientPolicy: clientpolicy.Policy{
			MaxExtractCount:  5,
			AllowedUpstreams: []string{"provider-a"},
			AllowedRegions:   []string{"shanghai"},
		},
	}
	if err := Validate(cfg); err != nil {
		t.Fatalf("Validate(distribution client policy) error = %v", err)
	}

	cfg.Distribution.Auth.ClientPolicy.AllowedUpstreams = []string{"missing"}
	if err := Validate(cfg); err == nil || !strings.Contains(err.Error(), "missing") {
		t.Fatalf("Validate(unknown allowed upstream) error = %v", err)
	}

	cfg.Distribution.Auth.ClientPolicy = clientpolicy.Policy{}
	cfg.Gateway.Auth = Auth{
		Mode: "bearer", Token: "gateway-token",
		ClientPolicy: clientpolicy.Policy{AllowedRoutings: []string{"extract"}},
	}
	cfg.Routing[0].Purpose = "gateway"
	if err := Validate(cfg); err != nil {
		t.Fatalf("Validate(gateway routing policy) error = %v", err)
	}
	cfg.Gateway.Auth.ClientPolicy.AllowedRoutings = []string{"missing"}
	if err := Validate(cfg); err == nil || !strings.Contains(err.Error(), "missing") {
		t.Fatalf("Validate(unknown gateway routing) error = %v", err)
	}
	cfg.Gateway.Auth.ClientPolicy = clientpolicy.Policy{MaxExtractCount: 1}
	if err := Validate(cfg); err == nil || !strings.Contains(err.Error(), "only supported on distribution") {
		t.Fatalf("Validate(gateway extraction policy) error = %v", err)
	}
}

func TestValidateMetricsListener(t *testing.T) {
	t.Parallel()
	cfg := mustLoadValidConfig(t)
	cfg.Metrics = Metrics{Enabled: true}
	if err := Validate(cfg); err == nil || !strings.Contains(err.Error(), "metrics listen") {
		t.Fatalf("Validate(metrics without listen) error = %v", err)
	}
	cfg.Metrics.Listen = "not-an-address"
	if err := Validate(cfg); err == nil || !strings.Contains(err.Error(), "metrics listen") {
		t.Fatalf("Validate(invalid metrics listen) error = %v", err)
	}
	cfg.Metrics.Listen = "127.0.0.1:70000"
	if err := Validate(cfg); err == nil || !strings.Contains(err.Error(), "metrics listen") {
		t.Fatalf("Validate(out-of-range metrics port) error = %v", err)
	}
	cfg.Metrics.Listen = "0.0.0.0:9090"
	if err := Validate(cfg); err != nil {
		t.Fatalf("Validate(public metrics listener) error = %v", err)
	}
	cfg.Metrics = Metrics{Enabled: false, Listen: "not-an-address"}
	if err := Validate(cfg); err != nil {
		t.Fatalf("Validate(disabled metrics listener) error = %v", err)
	}
}

func TestValidateControlPlane(t *testing.T) {
	tests := []struct {
		name   string
		mutate func(*Config)
		want   string
	}{
		{
			name: "missing listen",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validControlPlane()
				cfg.ControlPlane.Listen = ""
			},
			want: "controlPlane listen",
		},
		{
			name: "public plaintext",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validControlPlane()
				cfg.ControlPlane.Listen = "0.0.0.0:8443"
			},
			want: "requires mtls",
		},
		{
			name: "short session ttl",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validControlPlane()
				cfg.ControlPlane.SessionTTL = Duration(29 * time.Second)
			},
			want: "sessionTTL",
		},
		{
			name: "stale below heartbeat",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validControlPlane()
				cfg.ControlPlane.MaxStaleAge = Duration(9 * time.Second)
			},
			want: "maxStaleAge",
		},
		{
			name: "invalid protocol",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validControlPlane()
				cfg.ControlPlane.ProtocolVersion = 0
			},
			want: "protocolVersion",
		},
		{
			name: "invalid message limit",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validControlPlane()
				cfg.ControlPlane.MaxMessageBytes = 64<<20 + 1
			},
			want: "maxMessageBytes",
		},
		{
			name: "invalid counter limit",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validControlPlane()
				cfg.ControlPlane.MaxRuntimeCounters = MaximumPoolSize + 1
			},
			want: "maxRuntimeCounters",
		},
		{
			name: "zero concurrent streams",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validControlPlane()
				cfg.ControlPlane.MaxConcurrentStreams = 0
			},
			want: "maxConcurrentStreams",
		},
		{
			name: "unsupported tls mode",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validControlPlane()
				cfg.ControlPlane.TLS.Mode = "serverTLS"
			},
			want: "tls.mode",
		},
		{
			name: "missing mtls files",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validMTLSControlPlane()
				cfg.ControlPlane.TLS.CertFile = ""
			},
			want: "certFile",
		},
		{
			name: "trust domain with port",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validMTLSControlPlane()
				cfg.ControlPlane.TLS.TrustDomain = "proxy.example:443"
			},
			want: "trustDomain",
		},
		{
			name: "environment path",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validMTLSControlPlane()
				cfg.ControlPlane.TLS.Environment = "prod/eu"
			},
			want: "environment",
		},
		{
			name: "partial gateway tls",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validMTLSControlPlane()
				cfg.ControlPlane.GatewayTLS.CertFile = "/run/secrets/gateway-cert.pem"
			},
			want: "gatewayTLS",
		},
		{
			name: "partial checker tls",
			mutate: func(cfg *Config) {
				cfg.ControlPlane = validMTLSControlPlane()
				cfg.ControlPlane.CheckerTLS.KeyFile = "/run/secrets/checker-key.pem"
			},
			want: "checkerTLS",
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			cfg := mustLoadValidConfig(t)
			test.mutate(cfg)
			if err := Validate(cfg); err == nil || !strings.Contains(err.Error(), test.want) {
				t.Fatalf("Validate() error = %v, want substring %q", err, test.want)
			}
		})
	}
}

func validControlPlane() ControlPlane {
	return ControlPlane{
		Enabled:              true,
		Listen:               "127.0.0.1:8443",
		ProtocolVersion:      1,
		HeartbeatInterval:    Duration(10 * time.Second),
		SessionTTL:           Duration(30 * time.Second),
		MaxStaleAge:          Duration(10 * time.Second),
		MaxMessageBytes:      1 << 20,
		MaxRuntimeCounters:   100_000,
		MaxConcurrentStreams: 128,
		TLS:                  ControlPlaneTLS{Mode: "disabled"},
	}
}

func validMTLSControlPlane() ControlPlane {
	controlPlane := validControlPlane()
	controlPlane.Listen = "0.0.0.0:8443"
	controlPlane.TLS = ControlPlaneTLS{
		Mode:         "mtls",
		CertFile:     "/run/secrets/controller-cert.pem",
		KeyFile:      "/run/secrets/controller-key.pem",
		ClientCAFile: "/run/secrets/worker-ca.pem",
		TrustDomain:  "proxy.example",
		Environment:  "production",
	}
	return controlPlane
}

func TestValidateRejectsInvalidConfigurationMatrix(t *testing.T) {
	tests := []struct {
		name   string
		mutate func(*Config)
		want   string
	}{
		{
			name: "unsupported strategy type",
			mutate: func(cfg *Config) {
				cfg.Routing[0].Strategy.Type = "custom"
			},
			want: "strategy.type",
		},
		{
			name: "unsupported unavailable action",
			mutate: func(cfg *Config) {
				cfg.Routing[0].OnUnavailable.Action = "fallback"
			},
			want: "onUnavailable.action",
		},
		{
			name: "negative cumulative fetch limit",
			mutate: func(cfg *Config) {
				upstream := cfg.Upstreams["provider-a"]
				upstream.Fetch.MaxTotal = -1
				cfg.Upstreams["provider-a"] = upstream
			},
			want: "fetch.maxTotal",
		},
		{
			name: "negative gateway reserve",
			mutate: func(cfg *Config) {
				cfg.Distribution.Extraction.ReserveForGateway = -1
			},
			want: "reserveForGateway",
		},
		{
			name: "negative extraction idempotency ttl",
			mutate: func(cfg *Config) {
				cfg.Distribution.Extraction.IdempotencyTTL = Duration(-time.Second)
			},
			want: "idempotencyTTL",
		},
		{
			name: "enabled upstream without ttl",
			mutate: func(cfg *Config) {
				upstream := cfg.Upstreams["provider-a"]
				upstream.Lifecycle.TTL = 0
				cfg.Upstreams["provider-a"] = upstream
			},
			want: "lifecycle.ttl",
		},
		{
			name: "no enabled upstream",
			mutate: func(cfg *Config) {
				for name, upstream := range cfg.Upstreams {
					upstream.Enabled = false
					cfg.Upstreams[name] = upstream
				}
			},
			want: "enabled upstream",
		},
		{
			name: "invalid trusted proxy CIDR",
			mutate: func(cfg *Config) {
				cfg.Gateway.Access.TrustedProxies = []string{"not-a-cidr"}
			},
			want: "trustedProxies",
		},
		{
			name: "negative listener request limit",
			mutate: func(cfg *Config) {
				cfg.Distribution.Limits.RequestsPerMinute = -1
			},
			want: "requestsPerMinute",
		},
		{
			name: "listener request limit exceeds exact counter range",
			mutate: func(cfg *Config) {
				cfg.Distribution.Limits.RequestsPerMinutePerClient = int(MaximumExactCounter) + 1
			},
			want: "requestsPerMinutePerClient",
		},
		{
			name: "invalid client identification mode",
			mutate: func(cfg *Config) {
				cfg.Distribution.ClientIdentification.Mode = "header"
			},
			want: "clientIdentification.mode",
		},
		{
			name: "authenticated client without authentication",
			mutate: func(cfg *Config) {
				cfg.Distribution.Auth = Auth{Mode: "none"}
				cfg.Distribution.ClientIdentification.Mode = "authenticatedClient"
			},
			want: "authenticatedClient requires authentication",
		},
		{
			name: "invalid destination deny CIDR",
			mutate: func(cfg *Config) {
				cfg.Gateway.DestinationPolicy.DenyCIDRs = []string{"not-a-cidr"}
			},
			want: "denyCIDRs",
		},
		{
			name: "invalid destination allowed port",
			mutate: func(cfg *Config) {
				cfg.Gateway.DestinationPolicy.AllowedPorts = []uint16{443, 0}
			},
			want: "allowedPorts",
		},
		{
			name: "duplicate destination allowed port",
			mutate: func(cfg *Config) {
				cfg.Gateway.DestinationPolicy.AllowedPorts = []uint16{443, 443}
			},
			want: "allowedPorts",
		},
		{
			name: "unsupported routing purpose",
			mutate: func(cfg *Config) {
				cfg.Routing[0].Purpose = "custom"
			},
			want: "purpose",
		},
		{
			name: "unsupported sequential end behavior",
			mutate: func(cfg *Config) {
				cfg.Routing[0].Strategy.EndBehavior = "restart"
			},
			want: "endBehavior",
		},
		{
			name: "sequential requires two upstreams",
			mutate: func(cfg *Config) {
				cfg.Routing[0].Upstreams = []string{"provider-a"}
			},
			want: "at least two upstreams",
		},
		{
			name: "weighted strategy missing weight",
			mutate: func(cfg *Config) {
				cfg.Routing[0].Strategy = Strategy{Type: "weighted", Weights: map[string]int{}}
			},
			want: "weights",
		},
		{
			name: "weighted strategy unknown upstream",
			mutate: func(cfg *Config) {
				cfg.Routing[0].Strategy = Strategy{Type: "weighted", Weights: map[string]int{
					"provider-a": 1,
					"provider-b": 1,
					"provider-c": 1,
				}}
			},
			want: "provider-c",
		},
		{
			name: "weighted strategy nonpositive weight",
			mutate: func(cfg *Config) {
				cfg.Routing[0].Strategy = Strategy{Type: "weighted", Weights: map[string]int{"provider-a": 0}}
			},
			want: "weight",
		},
		{
			name: "negative fetch request interval",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Fetch.RequestInterval = Duration(-1) })
			},
			want: "requestInterval",
		},
		{
			name: "zero fetch timeout",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Fetch.Timeout = 0 })
			},
			want: "fetch.timeout",
		},
		{
			name: "zero fetch attempts",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Fetch.MaxAttempts = 0 })
			},
			want: "fetch.maxAttempts",
		},
		{
			name: "zero fetch concurrency",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Fetch.MaxInFlight = 0 })
			},
			want: "fetch.maxInFlight",
		},
		{
			name: "zero estimated IPs per call",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Fetch.EstimatedIPsPerCall = 0 })
			},
			want: "estimatedIPsPerCall",
		},
		{
			name: "estimated IPs exceed pool size",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) {
					upstream.Fetch.EstimatedIPsPerCall = upstream.Pool.MaxSize + 1
				})
			},
			want: "estimatedIPsPerCall",
		},
		{
			name: "pool exceeds runtime scan bound",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Pool.MaxSize = MaximumPoolSize + 1 })
			},
			want: "pool.maxSize",
		},
		{
			name: "zero refill interval",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Refill.ReconcileInterval = 0 })
			},
			want: "refill.reconcileInterval",
		},
		{
			name: "refill target does not exceed minimum",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) {
					upstream.Refill.TargetAvailableSlots = upstream.Refill.MinimumAvailableSlots
				})
			},
			want: "targetAvailableSlots",
		},
		{
			name: "refill target exceeds theoretical capacity",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) {
					upstream.Refill.TargetAvailableSlots = int64(upstream.Pool.MaxSize)*int64(upstream.Capacity.MaxConcurrencyPerProxy) + 1
				})
			},
			want: "targetAvailableSlots",
		},
		{
			name: "negative fetch response limit",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Fetch.MaxResponseBytes = -1 })
			},
			want: "maxResponseBytes",
		},
		{
			name: "negative template timeout",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Fetch.TemplateTimeout = Duration(-1) })
			},
			want: "templateTimeout",
		},
		{
			name: "fetch jitter over one hundred",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Fetch.Retry.Jitter = 101 })
			},
			want: "fetch.retry.jitter",
		},
		{
			name: "zero check interval",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Check.Interval = 0 })
			},
			want: "check.interval",
		},
		{
			name: "check jitter over one hundred",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Check.Jitter = 101 })
			},
			want: "check.jitter",
		},
		{
			name: "zero check concurrency",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Check.MaxInFlight = 0 })
			},
			want: "check.maxInFlight",
		},
		{
			name: "zero check timeout",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Check.Timeout = 0 })
			},
			want: "check.timeout",
		},
		{
			name: "zero check attempts",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Check.MaxAttempts = 0 })
			},
			want: "check.maxAttempts",
		},
		{
			name: "zero check failure threshold",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Check.MaxConsecutiveFailures = 0 })
			},
			want: "maxConsecutiveFailures",
		},
		{
			name: "negative unhealthy remove after",
			mutate: func(cfg *Config) {
				updateUpstream(cfg, func(upstream *Upstream) { upstream.Check.UnhealthyRemoveAfter = Duration(-time.Second) })
			},
			want: "unhealthyRemoveAfter",
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			cfg := mustLoadValidConfig(t)
			test.mutate(cfg)
			err := Validate(cfg)
			if err == nil || !strings.Contains(err.Error(), test.want) {
				t.Fatalf("Validate() error = %v, want substring %q", err, test.want)
			}
		})
	}
}

func TestValidateRejectsUnboundedUpstreamCardinality(t *testing.T) {
	cfg := mustLoadValidConfig(t)
	for index := len(cfg.Upstreams); index <= MaximumUpstreams; index++ {
		cfg.Upstreams[fmt.Sprintf("disabled-%d", index)] = Upstream{}
	}
	if err := Validate(cfg); err == nil || !strings.Contains(err.Error(), "upstream count") {
		t.Fatalf("Validate(too many upstreams) error = %v", err)
	}
}

func TestValidateRejectsCountersOutsideRedisExactRange(t *testing.T) {
	if strconv.IntSize < 64 {
		t.Skip("64-bit int is required for values above the Redis exact range")
	}
	tests := []struct {
		name   string
		mutate func(*Upstream)
	}{
		{name: "fetch total", mutate: func(upstream *Upstream) {
			upstream.Fetch.MaxTotal = int(MaximumExactCounter) + 1
		}},
		{name: "proxy concurrency", mutate: func(upstream *Upstream) {
			upstream.Capacity.MaxConcurrencyPerProxy = int(MaximumExactCounter) + 1
		}},
		{name: "minimum slots", mutate: func(upstream *Upstream) {
			upstream.Refill.MinimumAvailableSlots = MaximumExactCounter + 1
			upstream.Refill.TargetAvailableSlots = MaximumExactCounter + 2
		}},
		{name: "target slots", mutate: func(upstream *Upstream) {
			upstream.Capacity.MaxConcurrencyPerProxy = int(MaximumExactCounter)
			upstream.Pool.MaxSize = 1
			upstream.Refill.MinimumAvailableSlots = MaximumExactCounter
			upstream.Refill.TargetAvailableSlots = MaximumExactCounter + 1
		}},
		{name: "theoretical slots", mutate: func(upstream *Upstream) {
			upstream.Pool.MaxSize = 2
			upstream.Capacity.MaxConcurrencyPerProxy = int(MaximumExactCounter/2 + 1)
			upstream.Refill.MinimumAvailableSlots = 1
			upstream.Refill.TargetAvailableSlots = 2
		}},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			cfg := mustLoadValidConfig(t)
			updateUpstream(cfg, test.mutate)
			if err := Validate(cfg); err == nil || !strings.Contains(err.Error(), "exact counter range") {
				t.Fatalf("Validate(inexact counter) error = %v", err)
			}
		})
	}
}

func TestResolvedConfigFormattingRedactsSecrets(t *testing.T) {
	configured := strings.Replace(validConfig, `  auth:
    mode: none`, `  auth:
    mode: usernamePassword
    username: gateway-user
    password: "${GATEWAY_PASSWORD}"`, 1)
	configured = strings.Replace(configured, `  auth:
    mode: none`, `  auth:
    mode: apiKey
    header: X-API-Key
    token: "${DISTRIBUTION_TOKEN}"`, 1)
	configured = strings.Replace(configured, `      auth:
        type: none`, `      auth:
        type: apiKey
        location: header
        name: X-Provider-Key
        value: "${PROVIDER_API_KEY}"`, 1)
	resolver := fixtureResolver{environment: map[string]string{
		"GATEWAY_PASSWORD":   "password-marker",
		"DISTRIBUTION_TOKEN": "token-marker",
		"PROVIDER_API_KEY":   "api-key-marker",
	}}

	cfg, err := LoadResolved(strings.NewReader(configured), resolver)
	if err != nil {
		t.Fatalf("LoadResolved(): %v", err)
	}
	for _, format := range []string{"%v", "%+v", "%#v"} {
		formatted := fmt.Sprintf(format, cfg)
		for _, secret := range []string{"password-marker", "token-marker", "api-key-marker"} {
			if strings.Contains(formatted, secret) {
				t.Fatalf("format %q leaked secret %q: %s", format, secret, formatted)
			}
		}
		if !strings.Contains(formatted, "[REDACTED]") {
			t.Fatalf("format %q did not contain a redaction marker: %s", format, formatted)
		}
	}

	redacted := cfg.Redacted()
	if redacted.Gateway.Auth.Password != "[REDACTED]" ||
		redacted.Distribution.Auth.Token != "[REDACTED]" ||
		redacted.Upstreams["provider-a"].API.Auth.Value != "[REDACTED]" {
		t.Fatalf("Redacted() retained a secret: %+v", &redacted)
	}
	if cfg.Gateway.Auth.Password != "password-marker" {
		t.Fatal("Redacted() mutated the source configuration")
	}
}

func mustLoadValidConfig(t *testing.T) *Config {
	t.Helper()
	cfg, err := Load(strings.NewReader(validConfig))
	if err != nil {
		t.Fatalf("Load(validConfig): %v", err)
	}
	return cfg
}

func updateUpstream(cfg *Config, update func(*Upstream)) {
	upstream := cfg.Upstreams["provider-a"]
	update(&upstream)
	cfg.Upstreams["provider-a"] = upstream
}

type fixtureResolver struct {
	environment map[string]string
	files       map[string]string
}

func (r fixtureResolver) LookupEnv(name string) (string, bool) {
	value, ok := r.environment[name]
	return value, ok
}

func (r fixtureResolver) ReadFile(path string) ([]byte, error) {
	value, ok := r.files[path]
	if !ok {
		return nil, fmt.Errorf("fixture file %q not found", path)
	}
	return []byte(value), nil
}