package collector

import (
	"bee/audit/internal/schema"
	"log/slog"
	"os/exec"
	"regexp"
	"strings"
	"time"
)

// dmesg -T output: [Thu Jun 18 14:23:45 2026] message
// dmesg without -T: [  123.456789] message
var dmesgTimestampRE = regexp.MustCompile(`^\[([^\]]+)\]\s*(.*)$`)

// Keywords that indicate an error or hardware problem worth capturing.
var dmesgErrorPatterns = []*regexp.Regexp{
	regexp.MustCompile(`(?i)\berr(or)?\b`),
	regexp.MustCompile(`(?i)\bfail(ed|ure)?\b`),
	regexp.MustCompile(`(?i)\bfault\b`),
	regexp.MustCompile(`(?i)\bwarn(ing)?\b`),
	regexp.MustCompile(`(?i)\bAER\b`),
	regexp.MustCompile(`(?i)\bXid\b`),
	regexp.MustCompile(`(?i)\bNVRM\b`),
	regexp.MustCompile(`(?i)\bpanic\b`),
	regexp.MustCompile(`(?i)\bcorrected\b`),
	regexp.MustCompile(`(?i)\buncorrect`),
	regexp.MustCompile(`(?i)\bECC\b`),
	regexp.MustCompile(`(?i)\btimeout\b`),
	regexp.MustCompile(`(?i)\breset\b`),
	regexp.MustCompile(`(?i)\bdead\b`),
	regexp.MustCompile(`(?i)\bhang\b`),
	regexp.MustCompile(`(?i)\bstall\b`),
	regexp.MustCompile(`(?i)\bdisabled\b`),
}

// Boot-time messages below are noisy configuration/driver diagnostics, not
// hardware incidents.  Raw dmesg remains in the bundle, but presenting each
// of them as Critical makes the event log unusable.
var dmesgIgnorePatterns = []*regexp.Regexp{
	regexp.MustCompile(`(?i)bridge window .* failed to assign`),
	regexp.MustCompile(`(?i)^NVRM: loading NVIDIA .* Kernel Module`),
	regexp.MustCompile(`(?i)^NVRM: Persistence mode is deprecated`),
	regexp.MustCompile(`(?i)^nvidia: module verification failed:.*tainting kernel`),
	regexp.MustCompile(`(?i)^Yama: disabled by default`),
	regexp.MustCompile(`(?i)^ERST: .*initialized`),
	regexp.MustCompile(`(?i)iommu sva bind failed: -95`),
	regexp.MustCompile(`(?i)gpuClearFbhubPoisonIntrForBug`),
}

// collectDmesgErrors runs `dmesg -T` (or `dmesg` without -T on failure) and
// returns only lines that match known error/warning patterns.
func collectDmesgErrors() []schema.HardwareEventLog {
	out, err := exec.Command("dmesg", "-T").Output()
	if err != nil || len(out) == 0 {
		// Fallback: dmesg without human-readable timestamps
		out, err = exec.Command("dmesg").Output()
		if err != nil || len(out) == 0 {
			return nil
		}
	}
	entries := parseDmesgErrors(string(out))
	if len(entries) == 0 {
		return nil
	}
	slog.Info("dmesg: collected error entries", "count", len(entries))
	return entries
}

func parseDmesgErrors(output string) []schema.HardwareEventLog {
	var entries []schema.HardwareEventLog
	collectedAt := time.Now().UTC().Format(time.RFC3339)

	for _, line := range strings.Split(output, "\n") {
		line = strings.TrimSpace(line)
		if line == "" {
			continue
		}

		var timestamp, message string
		if m := dmesgTimestampRE.FindStringSubmatch(line); m != nil {
			timestamp = strings.TrimSpace(m[1])
			message = strings.TrimSpace(m[2])
		} else {
			message = line
		}

		if message == "" {
			continue
		}
		if !matchesAny(message, dmesgErrorPatterns) {
			continue
		}
		if matchesAny(message, dmesgIgnorePatterns) {
			continue
		}

		severity := dmesgSeverity(message)
		source := "dmesg"

		var eventTime *string
		if timestamp != "" {
			t := timestamp
			eventTime = &t
		} else {
			eventTime = &collectedAt
		}

		entries = append(entries, schema.HardwareEventLog{
			Source:    source,
			EventTime: eventTime,
			Severity:  &severity,
			Message:   message,
		})
	}
	return entries
}

func matchesAny(s string, patterns []*regexp.Regexp) bool {
	for _, p := range patterns {
		if p.MatchString(s) {
			return true
		}
	}
	return false
}

// dmesgSeverityCriticalPatterns use \b word boundaries, unlike a plain
// strings.Contains check, so common words that merely contain a keyword as a
// substring don't false-positive — e.g. "disabled by default" contains
// "fault" (de-fault), and "undead" would contain "dead".
var dmesgSeverityCriticalPatterns = []*regexp.Regexp{
	regexp.MustCompile(`(?i)\bpanic\b`),
	regexp.MustCompile(`(?i)\buncorrect`),
	regexp.MustCompile(`(?i)\bxid\b`),
	regexp.MustCompile(`(?i)\berror\b`),
	regexp.MustCompile(`(?i)\bfault\b`),
	regexp.MustCompile(`(?i)\bfail(ed|ure)?\b`),
	regexp.MustCompile(`(?i)\bdead\b`),
	regexp.MustCompile(`(?i)\bhang\b`),
}

func dmesgSeverity(msg string) string {
	if sev, ok := XidSeverity(msg); ok {
		if sev == "critical" {
			return statusCritical
		}
		return statusWarning
	}
	if matchesAny(msg, dmesgSeverityCriticalPatterns) {
		return statusCritical
	}
	return statusWarning
}