"cmd/go/internal/modfetch"
	"cmd/go/internal/modfetch/codehost"

	"golang.org/x/mod/module"
)

// cmpVersion implements the comparison for versions in the module loader.
//
// It is consistent with gover.ModCompare except that as a special case,
// the version "" is considered higher than all other versions.
// The main module (also known as the target) has no version and must be chosen

var isToolchainTests = []testCase1[string, bool]{
	{"go", true},
	{"toolchain", true},
	{"anything", false},
	{"golang.org/toolchain", false},
}

func TestModCompare(t *testing.T) { test3(t, modCompareTests, "ModCompare", ModCompare) }

var modCompareTests = []testCase3[string, string, string, int]{
	{"go", "1.2", "1.3", -1},
	{"go", "v1.2", "v1.3", 0}, // equal because invalid
	{"go", "1.2", "1.2", 0},
	{"toolchain", "go1.2", "go1.3", -1},

	return path == "go" || path == "toolchain"
}

// ModCompare returns the result of comparing the versions x and y
// for the module with the given path.
// The path is necessary because the "go" and "toolchain" modules
// use a different version syntax and semantics (gover, this package)
// than most modules (semver).
func ModCompare(path string, x, y string) int {
	if path == "go" {
		return Compare(x, y)
	}

		}
		qm.filter = func(mv string) bool { return gover.ModCompare(qm.path, mv, v) <= 0 }
		if !matchesMajor(v) {
			qm.preferIncompatible = true
		}

	case strings.HasPrefix(query, "<"):
		v := query[len("<"):]
		if !gover.ModIsValid(path, v) {
			return badVersion(v)
		}
		qm.filter = func(mv string) bool { return gover.ModCompare(qm.path, mv, v) < 0 }
		if !matchesMajor(v) {

			// the conflict. Find the next-lowest candidate and apply it.
			rejectedRoot[m] = true
			prev := m
			for {
				prev, err = previousVersion(ctx, prev)
				if gover.ModCompare(m.Path, m.Version, origV) > 0 && (gover.ModCompare(m.Path, prev.Version, origV) < 0 || err != nil) {
					// previousVersion skipped over origV. Insert it into the order.
					prev.Version = origV
				} else if err != nil {

	versions, err := r.Versions(ctx, "")
	if err != nil {
		return nil, err
	}
	var max string
	for _, v := range versions.List {
		if max == "" || gover.ModCompare(r.path, v, max) > 0 {
			max = v
		}
	}
	return r.Stat(ctx, max)
}

func (r *toolchainRepo) GoMod(ctx context.Context, version string) (data []byte, err error) {

		if i > 0 {
			prev := rootModules[i-1]
			if prev.Path > m.Path || (prev.Path == m.Path && gover.ModCompare(m.Path, prev.Version, m.Version) > 0) {
				panic(fmt.Sprintf("newRequirements called with unsorted roots: %v", rootModules))
			}
		}

		if v, ok := rs.maxRootVersion[m.Path]; ok && gover.ModCompare(m.Path, v, m.Version) >= 0 {
			continue
		}
		rs.maxRootVersion[m.Path] = m.Version
	}

				// is in the build list and is the selected version of its path.
				// If this information is new, record it.
				if v, ok := vendorVersion[mod.Path]; !ok || gover.ModCompare(mod.Path, v, mod.Version) < 0 {
					vendorList = append(vendorList, mod)
					vendorVersion[mod.Path] = mod.Version
				}
			}
		}
	})
}

	}
	summary, err := rawGoModSummary(rm)
	if err != nil {
		return err
	}

	var rationale []string
	isRetracted := false
	for _, r := range summary.retract {
		if gover.ModCompare(m.Path, r.Low, m.Version) <= 0 && gover.ModCompare(m.Path, m.Version, r.High) <= 0 {
			isRetracted = true
			if r.Rationale != "" {
				rationale = append(rationale, r.Rationale)
			}
		}
	}
	if isRetracted {

		// authenticated.
		return
	} else if err != nil {
		if m.Error == nil {
			m.Error = &modinfo.ModuleError{Err: err.Error()}
		}
		return
	}

	if gover.ModCompare(m.Path, info.Version, m.Version) > 0 {
		m.Update = &modinfo.ModulePublic{
			Path:    m.Path,
			Version: info.Version,
			Time:    &info.Time,
		}
	}
}