package main

import (
	"os"
	"path/filepath"
	"testing"
)

// The choice this program makes silently, and got wrong.
//
// findPython took the newest interpreter on the machine, with a floor and no
// ceiling - backwards, because the newest Python is the one least likely to
// have binary wheels. On a Mac holding Python 3.14 it chose 3.14, pip found
// no numpy wheel for cp314, fell back to a source build and produced two
// screens of clang errors ending in "<arm_neon.h> is intended only for ARM
// and AArch64 targets". The operator's machine was fine; the version was not.
func TestTooNewIsRefusedRatherThanCompiled(t *testing.T) {
	if got := pythonVerdict(3, maxMinor+1, true); got != verdictTooNew {
		t.Errorf("3.%d = %q, want %q - picking it means a source build",
			maxMinor+1, got, verdictTooNew)
	}
	if got := pythonVerdict(3, maxMinor, true); got != verdictOK {
		t.Errorf("3.%d = %q, want %q - the ceiling is inclusive", maxMinor, got, verdictOK)
	}
}

// Too old and too new must stay different answers. Telling somebody holding
// Python 3.14 that no Python was found, or that theirs is too old, sends them
// to install a newer one - which is the direction that already failed.
func TestOldAndNewAreDifferentAnswers(t *testing.T) {
	old := pythonVerdict(3, minMinor-1, true)
	fresh := pythonVerdict(3, maxMinor+1, true)
	if old == fresh {
		t.Fatalf("3.%d and 3.%d both reported %q", minMinor-1, maxMinor+1, old)
	}
	if old != verdictTooOld {
		t.Errorf("3.%d = %q, want %q", minMinor-1, old, verdictTooOld)
	}
}

// Every version in the range is accepted, so the window this program claims
// to support is the one it actually uses.
func TestTheWholeSupportedRangeIsAccepted(t *testing.T) {
	for m := minMinor; m <= maxMinor; m++ {
		if got := pythonVerdict(3, m, true); got != verdictOK {
			t.Errorf("3.%d = %q, want %q", m, got, verdictOK)
		}
	}
	if minMinor > maxMinor {
		t.Fatal("the supported range is empty; nothing would ever be chosen")
	}
}

// A major version nobody has tested against is not something to guess at, and
// an unreadable version string is not a working interpreter.
func TestUnknownVersionsAreNotAccepted(t *testing.T) {
	for _, c := range []struct {
		name         string
		major, minor int
		parsed       bool
	}{
		{"python 4", 4, 0, true},
		{"python 2", 2, 7, true},
		{"unparseable", 0, 0, false},
	} {
		if got := pythonVerdict(c.major, c.minor, c.parsed); got == verdictOK {
			t.Errorf("%s was accepted", c.name)
		}
	}
}

// An environment already on disk is reused, and that is right until the Python
// inside it is one this build cannot use.
//
// It was reused unconditionally, which would have defeated the ceiling above
// on the exact machine that found the bug: that Mac already had a runtime
// built by Python 3.14, left behind by the run that failed. Setup would pick a
// good interpreter, find the 3.14 environment, keep it, and die in the same
// clang error as before - a fix defeated by the wreckage of the bug it fixes.
//
// Real environments, not a fake: the thing under test is what an interpreter
// on disk reports about itself.
func TestAnUnsupportedEnvironmentIsNotReused(t *testing.T) {
	py, _, err := findPython()
	if err != nil {
		t.Skipf("no supported Python on this machine: %v", err)
	}
	venv := filepath.Join(t.TempDir(), "runtime")
	if err := makeVenv(py, venv); err != nil {
		t.Fatalf("makeVenv: %v", err)
	}
	if ok, ver := venvUsable(venv); !ok {
		t.Fatalf("an environment built from the interpreter setup just chose "+
			"reported itself unusable (%s)", ver)
	}

	// The two states that must not be confused with a working one.
	empty := filepath.Join(t.TempDir(), "gone")
	if ok, _ := venvUsable(empty); ok {
		t.Error("a missing environment was reported usable")
	}
	broken := filepath.Join(t.TempDir(), "broken")
	if err := os.MkdirAll(filepath.Dir(venvPython(broken)), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(venvPython(broken), []byte("not an interpreter"), 0o755); err != nil {
		t.Fatal(err)
	}
	if ok, ver := venvUsable(broken); ok {
		t.Errorf("a half-created environment was reported usable (%s)", ver)
	}
}