package httpdl

import (
	"crypto/sha256"
	"encoding/hex"
	"errors"
	"os"
	"path/filepath"
	"testing"
)

func TestParseChecksum(t *testing.T) {
	// A valid spec parses; the type and digest match case-insensitively.
	good := "SHA-256=" + hex.EncodeToString(make([]byte, 32))
	if _, want, err := parseChecksum(good); err != nil || len(want) != 64 {
		t.Fatalf("parseChecksum(%q) = %q, %v; want a 64-char digest and nil error", good, want, err)
	}
	full := hex.EncodeToString(make([]byte, 32))
	bad := map[string]string{
		"no '='":          "sha-256",
		"unknown type":    "sha-999=" + full,
		"wrong type name": "sha256=" + full, // the type is spelled sha-256
		"digest not hex":  "sha-256=zzzz",
		"wrong length":    "sha-256=abcd",
	}
	for name, spec := range bad {
		if _, _, err := parseChecksum(spec); err == nil {
			t.Errorf("%s: parseChecksum(%q) = nil error, want error", name, spec)
		}
	}
}

func TestValidChecksum(t *testing.T) {
	good := "sha-256=" + hex.EncodeToString(make([]byte, 32))
	if err := ValidChecksum(good); err != nil {
		t.Errorf("ValidChecksum(%q) = %v, want nil", good, err)
	}
	if err := ValidChecksum("crc32=deadbeef"); err == nil {
		t.Errorf("ValidChecksum(crc32): want error (unsupported type)")
	}
}

func TestVerifyFile(t *testing.T) {
	path := filepath.Join(t.TempDir(), "f")
	data := []byte("the data is the design")
	if err := os.WriteFile(path, data, 0o644); err != nil {
		t.Fatal(err)
	}
	sum := sha256.Sum256(data)

	// A matching digest verifies clean.
	if err := verifyFile(path, sha256.New, hex.EncodeToString(sum[:])); err != nil {
		t.Errorf("verifyFile match: %v", err)
	}
	// A wrong digest returns ErrChecksum, which main maps to exit code 32.
	wrong := hex.EncodeToString(make([]byte, 32))
	if err := verifyFile(path, sha256.New, wrong); !errors.Is(err, ErrChecksum) {
		t.Errorf("verifyFile mismatch = %v; want ErrChecksum", err)
	}
}