package config

import (
	"net/netip"
	"os"
	"reflect"
	"slices"
	"strings"
	"testing"
)

// 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_CACHE_MAX_BYTES", "1024")
	t.Setenv("PIXA_BLOCKED_NETWORKS", "203.0.113.0/24")
	t.Setenv("PIXA_TRUSTED_PROXIES", "192.0.2.0/24")

	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,
		CacheMaxBytes:              1024,
		cacheMaxBytesExplicit:      true,
		BlockedNetworks:            []netip.Prefix{netip.MustParsePrefix("203.0.113.0/24")},
		TrustedProxies:             []netip.Prefix{netip.MustParsePrefix("192.0.2.0/24")},
	}

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

// 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")
}

// 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())
	}
}