package config

import (
	"net/netip"
	"os"
	"path/filepath"
	"reflect"
	"slices"
	"strings"
	"testing"
	"time"

	"sneak.berlin/go/pixa/internal/globals"
	"sneak.berlin/go/pixa/internal/logger"
)

// TestMain unsets PORT and every PIXA_ environment variable before the
// tests run, so each test sees only the variables it sets itself, not
// whatever the shell running the tests exports.
func TestMain(m *testing.M) {
	for _, entry := range os.Environ() {
		name, _, _ := strings.Cut(entry, "=")
		if name != "PORT" && !strings.HasPrefix(name, "PIXA_") {
			continue
		}

		err := os.Unsetenv(name)
		if err != nil {
			panic(err)
		}
	}

	m.Run()
}

// wantStartupError fails the test unless err is a startup error that
// mentions every one of wants.
func wantStartupError(t *testing.T, err error, wants ...string) {
	t.Helper()

	if err == nil {
		t.Fatalf("want a startup error mentioning %q, got none", wants)
	}

	t.Logf("got expected error: %v", err)

	for _, want := range wants {
		if !strings.Contains(err.Error(), want) {
			t.Errorf("error %q does not mention %q", err.Error(), want)
		}
	}
}

// TestEnvironmentSetsEveryKey sets every key from its environment
// variable, with no config file at all: PORT for the port, and PIXA_
// plus the key in upper case, "." written as "_", for every other key.
func TestEnvironmentSetsEveryKey(t *testing.T) {
	t.Setenv("PIXA_DEBUG", "true")
	t.Setenv("PIXA_MAINTENANCE_MODE", "1")
	t.Setenv("PORT", "9090")
	t.Setenv("PIXA_STATE_DIR", "/srv/pixa-env")
	t.Setenv("PIXA_SENTRY_DSN", "https://abc123@sentry.example.com/42")
	t.Setenv("PIXA_DB_URL", "file:/srv/pixa-env/other.sqlite3")
	t.Setenv("PIXA_METRICS_USERNAME", "metricsuser")
	t.Setenv("PIXA_METRICS_PASSWORD", "metricspass")
	t.Setenv("PIXA_SIGNING_KEY", validTestSigningKey)
	t.Setenv("PIXA_ALLOWLIST_HOSTS", "s3.sneak.cloud,.example.com")
	t.Setenv("PIXA_ALLOW_HTTP", "true")
	t.Setenv("PIXA_UPSTREAM_CONNECTIONS_PER_HOST", "5")
	t.Setenv("PIXA_UPSTREAM_CONNECTIONS", "10")
	t.Setenv("PIXA_MAX_CONCURRENT_PROCESSING", "3")
	t.Setenv("PIXA_CACHE_MAX_BYTES", "1024")
	t.Setenv("PIXA_BLOCKED_NETWORKS", "203.0.113.0/24")
	t.Setenv("PIXA_TRUSTED_PROXIES", "192.0.2.0/24")
	t.Setenv("PIXA_ACCESS_CONTROL_ALLOW_ORIGIN", "https://app.example.com")
	t.Setenv("PIXA_UPSTREAM_FETCH_TIMEOUT", "10s")
	t.Setenv("PIXA_UPSTREAM_MAX_RESPONSE_SIZE", "1048576")
	t.Setenv("PIXA_DOWNSTREAM_TIMEOUT", "2m")

	c, err := newFromSmartConfig(nil)
	if err != nil {
		t.Fatalf("configuration from the environment alone should load: %v", err)
	}

	want := Config{
		Debug:                      true,
		MaintenanceMode:            true,
		Port:                       9090,
		StateDir:                   "/srv/pixa-env",
		SentryDSN:                  "https://abc123@sentry.example.com/42",
		DBURL:                      "file:/srv/pixa-env/other.sqlite3",
		MetricsUsername:            "metricsuser",
		MetricsPassword:            "metricspass",
		SigningKey:                 validTestSigningKey,
		AllowlistHosts:             []string{testHostS3, ".example.com"},
		AllowHTTP:                  true,
		UpstreamConnectionsPerHost: 5,
		UpstreamConnections:        10,
		MaxConcurrentProcessing:    3,
		CacheMaxBytes:              1024,
		cacheMaxBytesExplicit:      true,
		BlockedNetworks:            []netip.Prefix{netip.MustParsePrefix("203.0.113.0/24")},
		TrustedProxies:             []netip.Prefix{netip.MustParsePrefix("192.0.2.0/24")},
		AccessControlAllowOrigin:   "https://app.example.com",
		UpstreamFetchTimeout:       10 * time.Second,
		UpstreamMaxResponseSize:    1048576,
		DownstreamTimeout:          2 * time.Minute,
	}

	if !reflect.DeepEqual(*c, want) {
		t.Errorf("config from the environment =\n%+v\nwant\n%+v", *c, want)
	}
}

// TestUnknownPixaVariableAbortsStartup checks that a PIXA_ variable that
// is not a setting's variable, such as a misspelled one, aborts startup
// naming it, as an unknown config key does, instead of being ignored.
func TestUnknownPixaVariableAbortsStartup(t *testing.T) {
	t.Setenv("PIXA_TRUSTED_PROXY", "192.0.2.0/24")
	t.Setenv("PIXA_SIGNINGKEY", validTestSigningKey)

	err := validateKnownEnvVars()
	wantStartupError(t, err, "PIXA_TRUSTED_PROXY", "PIXA_SIGNINGKEY")
}

// TestPixaPortAbortsStartupPointingToPort checks that PIXA_PORT aborts
// startup with a message saying to use PORT, which sets the port.
func TestPixaPortAbortsStartupPointingToPort(t *testing.T) {
	t.Setenv("PIXA_PORT", "9090")

	err := validateKnownEnvVars()
	wantStartupError(t, err, "PIXA_PORT", "use PORT")
}

// TestSettingVariablesAndConfigPathAreAccepted checks that every
// setting's variable and PIXA_CONFIG_PATH pass the check for unknown
// PIXA_ variables. TestEnvironmentSetsEveryKey pins the names in the list.
func TestSettingVariablesAndConfigPathAreAccepted(t *testing.T) {
	// A config file's env section loaded by another test can leave a
	// PIXA_ variable set for the whole process, so every one is unset
	// here first; t.Setenv restores each when the test ends.
	for _, entry := range os.Environ() {
		name, _, _ := strings.Cut(entry, "=")
		if !strings.HasPrefix(name, "PIXA_") {
			continue
		}

		t.Setenv(name, "")

		err := os.Unsetenv(name)
		if err != nil {
			t.Fatalf("failed to unset %s: %v", name, err)
		}
	}

	t.Setenv("PIXA_CONFIG_PATH", "/etc/pixa/config.yml")

	for _, name := range envVarNames() {
		t.Setenv(name, "")
	}

	err := validateKnownEnvVars()
	if err != nil {
		t.Fatalf("PIXA_CONFIG_PATH and every setting's variable "+
			"must be accepted: %v", err)
	}
}

// configFromNew writes yamlContent to a temporary config file, points
// PIXA_CONFIG_PATH at it, and runs New, as the server does at startup.
// The state directory is a temporary one and the disk cache is off, so
// New succeeds unless something in the test is wrong.
func configFromNew(t *testing.T, yamlContent string) (*Config, error) {
	t.Helper()

	tmpDir := t.TempDir()
	configPath := filepath.Join(tmpDir, "config.yml")

	err := os.WriteFile(configPath, []byte(yamlContent), 0o600)
	if err != nil {
		t.Fatalf("failed to write test config: %v", err)
	}

	t.Setenv("PIXA_CONFIG_PATH", configPath)
	t.Setenv("PIXA_STATE_DIR", filepath.Join(tmpDir, "state"))
	t.Setenv("PIXA_CACHE_MAX_BYTES", "0")

	testLogger, err := logger.New(nil, logger.Params{Globals: &globals.Globals{}})
	if err != nil {
		t.Fatalf("failed to create logger: %v", err)
	}

	return New(nil, Params{Logger: testLogger})
}

// TestUnknownPixaVariableAbortsNew checks that New, which the server
// calls at startup, aborts on a misspelled PIXA_ variable.
func TestUnknownPixaVariableAbortsNew(t *testing.T) {
	t.Setenv("PIXA_TRUSTED_PROXY", "192.0.2.0/24")

	_, err := configFromNew(t, signingKeyLine)
	wantStartupError(t, err, "PIXA_TRUSTED_PROXY")
}

// TestUnknownPixaVariableInEnvSectionAbortsNew checks that New aborts
// on a misspelled PIXA_ name in the config file's env section, which
// loading the file sets as an environment variable.
func TestUnknownPixaVariableInEnvSectionAbortsNew(t *testing.T) {
	// The variable must be absent until the file loads. t.Setenv makes
	// sure the one the file sets is removed when the test ends.
	t.Setenv("PIXA_TRUSTED_PROXY", "")

	err := os.Unsetenv("PIXA_TRUSTED_PROXY")
	if err != nil {
		t.Fatalf("failed to unset PIXA_TRUSTED_PROXY: %v", err)
	}

	_, err = configFromNew(t, signingKeyLine+
		"env:\n  PIXA_TRUSTED_PROXY: 192.0.2.0/24\n")
	wantStartupError(t, err, "PIXA_TRUSTED_PROXY")
}

// TestPortFromEnvironmentOverridesConfigFile checks that PORT wins over
// the port in the config file.
func TestPortFromEnvironmentOverridesConfigFile(t *testing.T) {
	t.Setenv("PORT", "9090")

	c, err := configFromYAML(t, signingKeyLine+"port: 8080\n")
	if err != nil {
		t.Fatalf("PORT=9090 with port 8080 in the file should load: %v", err)
	}

	if c.Port != 9090 {
		t.Errorf("Port = %d, want 9090 from PORT, not 8080 from the file", c.Port)
	}
}

// TestInvalidPortFromEnvironmentAbortsStartup checks that a PORT that is
// not a number, or is outside the port range, aborts startup naming PORT
// and the value, even though the file's port is valid.
func TestInvalidPortFromEnvironmentAbortsStartup(t *testing.T) {
	t.Setenv("PORT", "banana")

	_, err := configFromYAML(t, signingKeyLine+"port: 8080\n")
	wantStartupError(t, err, "PORT", "banana")

	t.Setenv("PORT", "70000")

	_, err = configFromYAML(t, signingKeyLine+"port: 8080\n")
	wantStartupError(t, err, "PORT", "70000")
}

// TestListFromEnvironmentReplacesConfigFileList checks that a list
// variable replaces the file's list, split on commas with the spaces
// around each entry trimmed.
func TestListFromEnvironmentReplacesConfigFileList(t *testing.T) {
	t.Setenv("PIXA_ALLOWLIST_HOSTS", " cdn.example.com , .example.org ")

	c, err := configFromYAML(t, signingKeyLine+
		"allowlist_hosts:\n  - s3.sneak.cloud\n  - sneak.berlin\n")
	if err != nil {
		t.Fatalf("PIXA_ALLOWLIST_HOSTS should load: %v", err)
	}

	want := []string{"cdn.example.com", ".example.org"}
	if !slices.Equal(c.AllowlistHosts, want) {
		t.Errorf("AllowlistHosts = %v, want %v from PIXA_ALLOWLIST_HOSTS",
			c.AllowlistHosts, want)
	}
}

// TestInvalidBlockedNetworksFromEnvironmentAbortsStartup checks that an
// invalid CIDR, or an empty entry, in PIXA_BLOCKED_NETWORKS aborts
// startup naming the variable, as the same list in the file does.
func TestInvalidBlockedNetworksFromEnvironmentAbortsStartup(t *testing.T) {
	t.Setenv("PIXA_BLOCKED_NETWORKS", "203.0.113.0/24,not-a-cidr")

	_, err := configFromYAML(t, signingKeyLine)
	wantStartupError(t, err, "PIXA_BLOCKED_NETWORKS", "not-a-cidr")

	t.Setenv("PIXA_BLOCKED_NETWORKS", "203.0.113.0/24,,198.51.100.0/24")

	_, err = configFromYAML(t, signingKeyLine)
	wantStartupError(t, err, "PIXA_BLOCKED_NETWORKS")
}

// TestInvalidDebugFromEnvironmentAbortsStartup checks that a PIXA_DEBUG
// that strconv.ParseBool rejects aborts startup instead of defaulting.
func TestInvalidDebugFromEnvironmentAbortsStartup(t *testing.T) {
	t.Setenv("PIXA_DEBUG", "maybe")

	_, err := configFromYAML(t, signingKeyLine)
	wantStartupError(t, err, "PIXA_DEBUG", "maybe")
}

// TestInvalidOriginTimeoutOrSizeFromEnvironmentAbortsStartup checks that
// an invalid CORS origin, timeout or response size limit in its variable
// aborts startup naming the variable and the value.
func TestInvalidOriginTimeoutOrSizeFromEnvironmentAbortsStartup(t *testing.T) {
	cases := []struct {
		variable string
		value    string
	}{
		{"PIXA_ACCESS_CONTROL_ALLOW_ORIGIN", "example.com"},
		{"PIXA_UPSTREAM_FETCH_TIMEOUT", "soon"},
		{"PIXA_UPSTREAM_MAX_RESPONSE_SIZE", "50MB"},
		{"PIXA_DOWNSTREAM_TIMEOUT", "0s"},
	}

	for _, tc := range cases {
		t.Run(tc.variable, func(t *testing.T) {
			t.Setenv(tc.variable, tc.value)

			_, err := configFromYAML(t, signingKeyLine)
			wantStartupError(t, err, tc.variable, tc.value)
		})
	}
}

// TestConfigFileAloneBehavesAsBefore checks that with no variables set
// (TestMain unsets them) the config file's values are used and omitted
// keys take their defaults.
func TestConfigFileAloneBehavesAsBefore(t *testing.T) {
	t.Parallel()

	c, err := configFromYAML(t, signingKeyLine+"port: 9191\n")
	if err != nil {
		t.Fatalf("config file should load: %v", err)
	}

	if c.Port != 9191 {
		t.Errorf("Port = %d, want 9191 from the file", c.Port)
	}

	if c.StateDir != DefaultStateDir {
		t.Errorf("StateDir = %q, want default %q", c.StateDir, DefaultStateDir)
	}

	if !slices.Equal(c.TrustedProxies, defaultTrustedProxies()) {
		t.Errorf("TrustedProxies = %v, want default %v",
			c.TrustedProxies, defaultTrustedProxies())
	}
}

// TestEmptyTrustedProxiesFromEnvironmentTrustsNoOne checks that an empty
// PIXA_TRUSTED_PROXIES is an empty list, like [] in the file: it trusts
// no proxy instead of taking the default ranges.
func TestEmptyTrustedProxiesFromEnvironmentTrustsNoOne(t *testing.T) {
	t.Setenv("PIXA_TRUSTED_PROXIES", "")

	c, err := configFromYAML(t, signingKeyLine)
	if err != nil {
		t.Fatalf("empty PIXA_TRUSTED_PROXIES should load: %v", err)
	}

	if len(c.TrustedProxies) != 0 {
		t.Errorf("TrustedProxies = %v, want none", c.TrustedProxies)
	}
}

// TestEmptyVariableDoesNotFallBackToConfigFile checks that a variable
// that is present but empty is a set value: an empty PIXA_STATE_DIR
// aborts startup like state_dir: "" in the file, instead of falling
// through to the file's state_dir.
func TestEmptyVariableDoesNotFallBackToConfigFile(t *testing.T) {
	t.Setenv("PIXA_STATE_DIR", "")

	_, err := configFromYAML(t, signingKeyLine+"state_dir: /srv/pixa-file\n")
	wantStartupError(t, err, "PIXA_STATE_DIR")
}

// TestMissingSigningKeyNamesItsVariable checks that with no config file
// and no PIXA_SIGNING_KEY, startup aborts naming the variable, which is
// how a container started without it reports the problem.
func TestMissingSigningKeyNamesItsVariable(t *testing.T) {
	t.Parallel()

	_, err := newFromSmartConfig(nil)
	wantStartupError(t, err, "PIXA_SIGNING_KEY")
}

// TestSecretsFromEnvironmentAreNotPrinted checks that errors about the
// signing key and the metrics password name their variables but never
// print their values.
func TestSecretsFromEnvironmentAreNotPrinted(t *testing.T) {
	t.Setenv("PIXA_SIGNING_KEY", "short-signing-secret")

	_, err := newFromSmartConfig(nil)
	wantStartupError(t, err, "PIXA_SIGNING_KEY")

	if strings.Contains(err.Error(), "short-signing-secret") {
		t.Errorf("error %q prints the signing key", err.Error())
	}

	t.Setenv("PIXA_SIGNING_KEY", validTestSigningKey)
	t.Setenv("PIXA_METRICS_PASSWORD", "metrics-password-secret")

	_, err = newFromSmartConfig(nil)
	wantStartupError(t, err, "PIXA_METRICS_PASSWORD")

	if strings.Contains(err.Error(), "metrics-password-secret") {
		t.Errorf("error %q prints the metrics password", err.Error())
	}
}