package bundle

import (
	"path/filepath"
	"strings"
)

// allowlist.go holds the known-benign-pattern allowlist that controls the
// false-positive blast radius of bundle scanning. Many legitimate skills ship a
// native wheel, run curl|sh against their own release host, set soffice
// LD_PRELOAD for document conversion, or point pip/npm at a corporate mirror.
// These benign-but-scary idioms share surface features with attacks; the
// allowlist downgrades matching findings so the scanner is not an FP cannon that
// forces operators to globally suppress bundle_cross_file.
//
// SAFETY INVARIANT: the defanged exfil host (attacker.example, 198.51.100.0/24
// TEST-NET) is NEVER allowlisted, so a downgrade can never launder a real exfil
// signal.

// knownBenignHosts are package-registry/CDN hosts treated as legitimate mirror
// targets. A registry rewrite to one of these is a corporate-mirror idiom, not
// an attack. Matching is host-suffix aware (registry.corp.example matches an
// entry "corp.example") via isKnownBenignHost.
var knownBenignHosts = map[string]bool{
	// Default public registries (rewriting "to" the default is a no-op, but the
	// string still appears in legit configs).
	"registry.npmjs.org":     true,
	"pypi.org":               true,
	"files.pythonhosted.org": true,
	"rubygems.org":           true,
	"crates.io":              true,
	"static.crates.io":       true,
	"proxy.golang.org":       true,
	"sum.golang.org":         true,
	"repo.maven.apache.org":  true,
	"repo1.maven.org":        true,
	// Common trusted release/CDN hosts skills legitimately curl from.
	"github.com":                    true,
	"raw.githubusercontent.com":     true,
	"objects.githubusercontent.com": true,
	"codeload.github.com":           true,
	"registry.yarnpkg.com":          true,
	"cdn.jsdelivr.net":              true,
	"unpkg.com":                     true,
}

// benignHostSuffixes are corporate/enterprise mirror domains that legitimately
// host private registries. A rewrite to a sub-host of one of these is a
// known-benign corporate-mirror pattern.
var benignHostSuffixes = []string{
	"jfrog.io",
	"artifactory.com",
	"pkg.dev",   // Google Artifact Registry
	"azure.com", // Azure Artifacts
	"visualstudio.com",
	"nexus.example", // documented corporate-mirror placeholder in the corpus
	"corp.example",  // documented corporate-mirror placeholder in the corpus
}

// disallowedExfilHostFragments are NEVER allowlisted regardless of any other
// rule (defense against an allowlist entry accidentally covering the corpus's
// defanged exfil host).
var disallowedExfilHostFragments = []string{
	"attacker.example",
	"198.51.100.",
}

// isKnownBenignHost reports whether host (already lowercased, no scheme/path) is
// a recognized legitimate registry/CDN/corporate-mirror. The defanged exfil host
// is explicitly excluded.
func isKnownBenignHost(host string) bool {
	host = strings.ToLower(strings.TrimSpace(host))
	if host == "" {
		return false
	}
	// Strip a port if present.
	if i := strings.IndexByte(host, ':'); i >= 0 {
		host = host[:i]
	}
	for _, frag := range disallowedExfilHostFragments {
		if strings.Contains(host, frag) {
			return false
		}
	}
	if knownBenignHosts[host] {
		return true
	}
	for _, suf := range benignHostSuffixes {
		if host == suf || strings.HasSuffix(host, "."+suf) {
			return true
		}
	}
	return false
}

// internalHostSuffixes are multi-label corporate/private-network suffixes that
// indicate an internal mirror rather than a public exfil host. A registry
// rewrite pointing at one of these is the enterprise "configure the internal
// cache" idiom (e.g. pypi.internal.example.com, registry.internal.example.com)
// and must not corroborate on its own.
var internalHostSuffixes = []string{
	".internal",    // bare *.internal
	".intra",       // *.intra
	".corp",        // *.corp
	".lan",         // *.lan
	".home.arpa",   // RFC 8375 home-network reserved zone
	".localdomain", // common single-host local suffix
}

// internalHostInfixes are multi-label internal markers that appear as an inner
// label rather than a trailing suffix, e.g. "internal" in
// pypi.internal.example.com / registry.internal.example.com (the corpus's
// corporate-mirror placeholder). Matched as a dot-delimited label so a host like
// "internalattacker.example" does NOT match.
var internalHostInfixes = []string{
	".internal.",
	".intra.",
	".corp.",
}

// isInternalRegistryHost reports whether host (lowercased, no scheme/path) is an
// internal/private registry mirror destination: an RFC1918 / loopback IP, a
// localhost name, or a host under an internal/corp suffix or infix. A rewrite to
// such a host is a benign enterprise mirror idiom and must NOT corroborate.
//
// SAFETY: the defanged exfil host (attacker.example, 198.51.100.0/24 TEST-NET)
// is checked FIRST and can never be classified as internal, so a real exfil
// signal can never be laundered through this downgrade.
func isInternalRegistryHost(host string) bool {
	host = strings.ToLower(strings.TrimSpace(host))
	if host == "" {
		return false
	}
	// Unwrap a bracketed IPv6 literal, optionally followed by ":port".
	if strings.HasPrefix(host, "[") {
		if end := strings.IndexByte(host, ']'); end >= 0 {
			host = host[1:end]
		} else {
			host = strings.TrimLeft(host, "[")
		}
	} else if strings.Count(host, ":") == 1 {
		// A single colon is a host:port separator (bare IPv6 has >=2 colons).
		host = host[:strings.IndexByte(host, ':')]
	}
	if host == "" {
		return false
	}
	// SAFETY GUARD FIRST: never downgrade the defanged exfil host.
	for _, frag := range disallowedExfilHostFragments {
		if strings.Contains(host, frag) {
			return false
		}
	}
	// Loopback / localhost names and literals.
	if host == "localhost" || host == "127.0.0.1" || host == "::1" ||
		strings.HasSuffix(host, ".localhost") {
		return true
	}
	// RFC1918 private IPv4 ranges.
	if isPrivateIPv4(host) {
		return true
	}
	// Internal/corp multi-label suffixes (trailing).
	for _, suf := range internalHostSuffixes {
		if strings.HasSuffix(host, suf) {
			return true
		}
	}
	// Internal/corp markers as an inner label (e.g. *.internal.example.com).
	for _, inf := range internalHostInfixes {
		if strings.Contains(host, inf) {
			return true
		}
	}
	return false
}

// isPrivateIPv4 reports whether host is a dotted-quad in an RFC1918 private
// range: 10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16. Non-IP hosts return
// false.
func isPrivateIPv4(host string) bool {
	parts := strings.Split(host, ".")
	if len(parts) != 4 {
		return false
	}
	octets := make([]int, 4)
	for i, p := range parts {
		if p == "" || len(p) > 3 {
			return false
		}
		n := 0
		for _, c := range p {
			if c < '0' || c > '9' {
				return false
			}
			n = n*10 + int(c-'0')
		}
		if n > 255 {
			return false
		}
		octets[i] = n
	}
	switch {
	case octets[0] == 10:
		return true
	case octets[0] == 172 && octets[1] >= 16 && octets[1] <= 31:
		return true
	case octets[0] == 192 && octets[1] == 168:
		return true
	}
	return false
}

// isKnownBenignNativePattern reports whether a native binary file matches a
// common legitimate shipping pattern (a signed/platform-tagged native wheel or
// a Node native addon) so a bare .so does not self-escalate. This is a
// precision lever only: a binary that embeds the exfil host or dangerous
// symbols is handled by the analyzer BEFORE this downgrade is consulted.
func isKnownBenignNativePattern(f *File) bool {
	if f == nil {
		return false
	}
	base := strings.ToLower(filepath.Base(f.RelPath))
	// Node native addon convention.
	if strings.HasSuffix(base, ".node") {
		return true
	}
	// Python extension modules carry an ABI tag, e.g.
	// "_speedups.cpython-312-x86_64-linux-gnu.so" or "...-darwin.so".
	if strings.HasSuffix(base, ".so") || strings.HasSuffix(base, ".dylib") {
		if strings.Contains(base, ".cpython-") ||
			strings.Contains(base, ".abi3.") ||
			strings.Contains(base, "-x86_64-") ||
			strings.Contains(base, "-aarch64-") ||
			strings.Contains(base, "-arm64-") ||
			strings.Contains(base, "-darwin") ||
			strings.Contains(base, "-linux-gnu") {
			return true
		}
	}
	return false
}

// isKnownBenignScriptIdiom reports whether a script line matches a benign-but-
// scary idiom that should not, on its own, escalate. Examples: setting
// LD_PRELOAD for soffice/libreoffice document conversion, or rustup/nvm-style
// installers fetching from their own canonical host. Lines containing the
// defanged exfil host are never benign.
func isKnownBenignScriptIdiom(line string) bool {
	low := strings.ToLower(line)
	for _, frag := range disallowedExfilHostFragments {
		if strings.Contains(low, frag) {
			return false
		}
	}
	// soffice/libreoffice LD_PRELOAD doc-conversion idiom.
	if strings.Contains(low, "ld_preload") &&
		(strings.Contains(low, "soffice") || strings.Contains(low, "libreoffice") ||
			strings.Contains(low, "unoconv")) {
		return true
	}
	// Canonical first-party installers fetched from their own hosts.
	benignInstallerHosts := []string{
		"sh.rustup.rs", "static.rust-lang.org",
		"raw.githubusercontent.com/nvm-sh",
		"get.docker.com", "deb.nodesource.com", "rpm.nodesource.com",
		"install.python-poetry.org",
	}
	if matchedAny(low, benignInstallerHosts) {
		return true
	}
	return false
}