package config

import (
	"fmt"
	"runtime"
	"testing"
)

// The variables that set the two concurrency limits.
const (
	testMaxConcurrentProcessingVar = "PIXA_MAX_CONCURRENT_PROCESSING"
	testUpstreamConnectionsVar     = "PIXA_UPSTREAM_CONNECTIONS"
)

// TestOmittedConcurrencyLimitsUseDefaults checks that an omitted
// max_concurrent_processing is half the CPUs Go uses, and at least 1, and
// an omitted upstream_connections is 64.
func TestOmittedConcurrencyLimitsUseDefaults(t *testing.T) {
	t.Parallel()

	c, err := configFromYAML(t, signingKeyLine)
	if err != nil {
		t.Fatalf("minimal config should be valid, got error: %v", err)
	}

	if c.MaxConcurrentProcessing != max(runtime.GOMAXPROCS(0)/2, 1) {
		t.Errorf("MaxConcurrentProcessing = %d, want %d, half the CPUs",
			c.MaxConcurrentProcessing, max(runtime.GOMAXPROCS(0)/2, 1))
	}

	if c.UpstreamConnections != 64 {
		t.Errorf("UpstreamConnections = %d, want 64", c.UpstreamConnections)
	}
}

// TestOmittedMaxConcurrentProcessingIsHalfTheCPUsAndAtLeastOne checks
// that an omitted max_concurrent_processing is half the CPUs Go uses,
// rounded down, and 1 when Go uses one CPU.
//
//nolint:paralleltest // it sets GOMAXPROCS, which other tests read
func TestOmittedMaxConcurrentProcessingIsHalfTheCPUsAndAtLeastOne(t *testing.T) {
	cpusBefore := runtime.GOMAXPROCS(0)

	t.Cleanup(func() { runtime.GOMAXPROCS(cpusBefore) })

	for _, tc := range []struct{ cpus, want int }{
		{1, 1}, {2, 1}, {3, 1}, {8, 4},
	} {
		runtime.GOMAXPROCS(tc.cpus)

		c, err := configFromYAML(t, signingKeyLine)
		if err != nil {
			t.Fatalf("minimal config should be valid, got error: %v", err)
		}

		t.Logf("GOMAXPROCS %d: MaxConcurrentProcessing %d",
			tc.cpus, c.MaxConcurrentProcessing)

		if c.MaxConcurrentProcessing != tc.want {
			t.Errorf("GOMAXPROCS %d: MaxConcurrentProcessing = %d, want %d",
				tc.cpus, c.MaxConcurrentProcessing, tc.want)
		}
	}
}

// TestExplicitConcurrencyLimitsAreUsed checks that valid values for the
// two limits are used as given.
func TestExplicitConcurrencyLimitsAreUsed(t *testing.T) {
	t.Parallel()

	c, err := configFromYAML(t, signingKeyLine+
		"max_concurrent_processing: 3\nupstream_connections: 10\n")
	if err != nil {
		t.Fatalf("valid config should load, got error: %v", err)
	}

	if c.MaxConcurrentProcessing != 3 {
		t.Errorf("MaxConcurrentProcessing = %d, want 3", c.MaxConcurrentProcessing)
	}

	if c.UpstreamConnections != 10 {
		t.Errorf("UpstreamConnections = %d, want 10", c.UpstreamConnections)
	}
}

// TestInvalidConcurrencyLimitAbortsStartup checks that a limit that is
// not a whole number of at least 1, or is null, aborts startup naming the
// key and the value, and the variable too where the value could have come
// from it.
func TestInvalidConcurrencyLimitAbortsStartup(t *testing.T) {
	t.Parallel()

	processing := keyMaxConcurrentProcessing
	connections := keyUpstreamConnections

	runAbortCases(t, []abortCase{
		{
			name: "max_concurrent_processing zero",
			yaml: signingKeyLine + processing + ": 0\n",
			wantErrSubstrings: []string{
				processing, testMaxConcurrentProcessingVar, "value 0",
			},
		},
		{
			name: "max_concurrent_processing negative",
			yaml: signingKeyLine + processing + ": -2\n",
			wantErrSubstrings: []string{
				processing, testMaxConcurrentProcessingVar, "value -2",
			},
		},
		{
			name: "max_concurrent_processing not a number",
			yaml: signingKeyLine + processing + ": lots\n",
			wantErrSubstrings: []string{
				processing, testMaxConcurrentProcessingVar, "lots",
			},
		},
		{
			name:              "max_concurrent_processing fractional",
			yaml:              signingKeyLine + processing + ": 1.5\n",
			wantErrSubstrings: []string{processing, "1.5"},
		},
		{
			name:              "max_concurrent_processing null",
			yaml:              signingKeyLine + processing + ": null\n",
			wantErrSubstrings: []string{processing, nullValueText},
		},
		{
			name: "upstream_connections zero",
			yaml: signingKeyLine + connections + ": 0\n",
			wantErrSubstrings: []string{
				connections, testUpstreamConnectionsVar, "value 0",
			},
		},
		{
			name: "upstream_connections negative",
			yaml: signingKeyLine + connections + ": -5\n",
			wantErrSubstrings: []string{
				connections, testUpstreamConnectionsVar, "value -5",
			},
		},
		{
			name: "upstream_connections not a number",
			yaml: signingKeyLine + connections + ": many\n",
			wantErrSubstrings: []string{
				connections, testUpstreamConnectionsVar, "many",
			},
		},
		{
			name:              "upstream_connections null",
			yaml:              signingKeyLine + connections + ": null\n",
			wantErrSubstrings: []string{connections, nullValueText},
		},
	})
}

// TestConcurrencyLimitsFromEnvironment checks that the two variables set
// the limits over the config file, and that an invalid value in either
// aborts startup naming the variable and the value.
func TestConcurrencyLimitsFromEnvironment(t *testing.T) {
	t.Setenv(testMaxConcurrentProcessingVar, "3")
	t.Setenv(testUpstreamConnectionsVar, "10")

	c, err := configFromYAML(t, signingKeyLine+
		"max_concurrent_processing: 5\nupstream_connections: 50\n")
	if err != nil {
		t.Fatalf("limits from the environment should load: %v", err)
	}

	if c.MaxConcurrentProcessing != 3 || c.UpstreamConnections != 10 {
		t.Errorf("limits = %d and %d, want 3 and 10 from the environment",
			c.MaxConcurrentProcessing, c.UpstreamConnections)
	}

	cases := []struct {
		variable string
		value    string
	}{
		{testMaxConcurrentProcessingVar, "lots"},
		{testMaxConcurrentProcessingVar, "0"},
		{testUpstreamConnectionsVar, "-1"},
		{testUpstreamConnectionsVar, "ten"},
	}

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

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

// TestInvalidMaxConcurrentProcessingFromEnvironmentAbortsStartup checks
// that a PIXA_MAX_CONCURRENT_PROCESSING that is not a whole number of at
// least 1, an empty one included, aborts startup naming the variable and
// the key instead of taking the default.
func TestInvalidMaxConcurrentProcessingFromEnvironmentAbortsStartup(t *testing.T) {
	for _, value := range []string{"", " ", "0.5", "half", "-1", "4 images"} {
		t.Run(fmt.Sprintf("value %q", value), func(t *testing.T) {
			t.Setenv(testMaxConcurrentProcessingVar, value)

			_, err := configFromYAML(t, signingKeyLine)
			wantStartupError(t, err,
				testMaxConcurrentProcessingVar, keyMaxConcurrentProcessing)
		})
	}
}