package inspur

import (
	"encoding/csv"
	"sort"
	"strings"
	"time"
	"unicode"

	"git.mchus.pro/mchus/logpile/internal/models"
	"git.mchus.pro/mchus/logpile/internal/parser"
)

// ParseSELList parses selelist.csv file with SEL events
// Format: ID, Date (MM/DD/YYYY), Time (HH:MM:SS), Sensor, Event, Status
// Example: 1,04/18/2025,09:31:18,Event Logging Disabled SEL_Status,Log area reset/cleared,Asserted
func ParseSELList(content []byte) []models.Event {
	return ParseSELListWithLocation(content, parser.DefaultArchiveLocation())
}

// ParseSELListWithLocation parses selelist.csv using provided source timezone
// for timestamps that don't contain an explicit offset.
func ParseSELListWithLocation(content []byte, location *time.Location) []models.Event {
	return parseSELList(content, func(local time.Time) *time.Location { return location })
}

func parseSELListWithResolver(content []byte, resolver *inspurTimezoneResolver) []models.Event {
	return parseSELList(content, resolver.locationFor)
}

func parseSELList(content []byte, locationFor func(time.Time) *time.Location) []models.Event {
	var events []models.Event

	text := string(content)
	lines := strings.Split(text, "\n")

	// Skip header line(s) if present
	startIdx := 0
	for i, line := range lines {
		if strings.Contains(strings.ToLower(line), "sel elist") {
			startIdx = i + 1
			break
		}
	}

	// Parse CSV data
	for i := startIdx; i < len(lines); i++ {
		line := strings.TrimSpace(lines[i])
		if line == "" {
			continue
		}

		// Parse CSV line
		r := csv.NewReader(strings.NewReader(line))
		records, err := r.Read()
		if err != nil || len(records) < 6 {
			continue
		}

		eventID := strings.TrimSpace(records[0])
		dateStr := strings.TrimSpace(records[1])
		timeStr := strings.TrimSpace(records[2])
		sensorStr := strings.TrimSpace(records[3])
		eventDesc := strings.TrimSpace(records[4])
		status := strings.TrimSpace(records[5])

		// Parse timestamp: MM/DD/YYYY HH:MM:SS
		timestamp := parseSELTimestampWithResolver(dateStr, timeStr, locationFor)

		// Extract sensor type and name
		sensorType, sensorName := parseSensorInfo(sensorStr)

		// Determine severity
		severity := determineSELSeverity(sensorStr, eventDesc, status)

		// Build full description
		description := buildSELDescription(eventDesc, status)

		events = append(events, models.Event{
			ID:          eventID,
			Timestamp:   timestamp,
			Source:      "SEL",
			SensorType:  sensorType,
			SensorName:  sensorName,
			EventType:   eventDesc,
			Severity:    severity,
			Description: description,
			RawData:     line,
		})
	}

	return events
}

func parseSELTimestampWithResolver(dateStr, timeStr string, locationFor func(time.Time) *time.Location) time.Time {
	timestampStr := dateStr + " " + timeStr
	local, err := time.ParseInLocation("01/02/2006 15:04:05", timestampStr, time.UTC)
	if err != nil {
		return time.Time{}
	}
	location := parser.DefaultArchiveLocation()
	if locationFor != nil {
		if resolved := locationFor(local); resolved != nil {
			location = resolved
		}
	}
	return time.Date(local.Year(), local.Month(), local.Day(), local.Hour(), local.Minute(), local.Second(), 0, location)
}

// parseSELTimestamp parses MM/DD/YYYY and HH:MM:SS into time.Time
func parseSELTimestamp(dateStr, timeStr string, location *time.Location) time.Time {
	return parseSELTimestampWithResolver(dateStr, timeStr, func(time.Time) *time.Location { return location })
}

// parseSensorInfo extracts sensor type and name from sensor string
// Example: "Event Logging Disabled SEL_Status" -> ("sel", "SEL_Status")
// Example: "Power Supply PSU0_Status" -> ("power_supply", "PSU0_Status")
func parseSensorInfo(sensorStr string) (sensorType, sensorName string) {
	parts := strings.Fields(sensorStr)
	if len(parts) == 0 {
		return "unknown", sensorStr
	}

	// Last part is usually the sensor name
	sensorName = parts[len(parts)-1]

	// First parts form the sensor type
	if len(parts) > 1 {
		sensorType = strings.ToLower(strings.Join(parts[:len(parts)-1], "_"))
	} else {
		sensorType = "system"
	}

	return
}

// determineSELSeverity determines event severity based on sensor and event description
func determineSELSeverity(sensorStr, eventDesc, status string) models.Severity {
	lowerSensor := strings.ToLower(sensorStr)
	lowerEvent := strings.ToLower(eventDesc)
	lowerStatus := strings.ToLower(status)
	if strings.Contains(lowerStatus, "deassert") {
		return models.SeverityInfo
	}

	// Critical indicators
	criticalKeywords := []string{
		"critical", "failure", "fault", "error",
		"ac lost", "predictive failure", "redundancy lost",
		"going high", "going low", "transition to critical",
	}

	for _, keyword := range criticalKeywords {
		if strings.Contains(lowerSensor, keyword) ||
			strings.Contains(lowerEvent, keyword) ||
			strings.Contains(lowerStatus, keyword) {
			return models.SeverityCritical
		}
	}

	// Warning indicators
	warningKeywords := []string{
		"warning", "disabled", "non-recoverable",
		"device removed", "device absent",
	}

	for _, keyword := range warningKeywords {
		if strings.Contains(lowerSensor, keyword) ||
			strings.Contains(lowerEvent, keyword) ||
			strings.Contains(lowerStatus, keyword) {
			return models.SeverityWarning
		}
	}

	// Info indicators (normal operations)
	infoKeywords := []string{
		"presence detected", "device present", "asserted",
		"initiated by", "state asserted", "s0/g0: working",
		"power button pressed",
	}

	for _, keyword := range infoKeywords {
		if strings.Contains(lowerEvent, keyword) ||
			strings.Contains(lowerStatus, keyword) {
			return models.SeverityInfo
		}
	}

	// Default to info
	return models.SeverityInfo
}

// dedupSELEvents removes exact SEL repeats and equivalent IDL/SEL copies at
// the same normalized instant. IDL is preferred because it carries an
// explicit timezone offset and usually a richer component-prefixed message.
func dedupSELEvents(events []models.Event) []models.Event {
	if len(events) == 0 {
		return events
	}
	out := make([]models.Event, 0, len(events))
	bySecond := make(map[int64][]int)
	for _, e := range events {
		if e.Timestamp.IsZero() {
			out = append(out, e)
			continue
		}

		second := e.Timestamp.Unix()
		duplicate := false
		for _, idx := range bySecond[second] {
			previous := out[idx]
			if !equivalentInspurEvent(previous, e) {
				continue
			}
			if previous.Source == "SEL" && e.Source != "SEL" {
				out[idx] = e
			}
			duplicate = true
			break
		}
		if duplicate {
			continue
		}
		bySecond[second] = append(bySecond[second], len(out))
		out = append(out, e)
	}
	return out
}

func equivalentInspurEvent(a, b models.Event) bool {
	if a.Source != "SEL" && b.Source != "SEL" {
		return false
	}
	if a.Severity != b.Severity || eventDirection(a) != eventDirection(b) {
		return false
	}
	left := normalizeEventDescription(a.Description)
	right := normalizeEventDescription(b.Description)
	if left == "" || right == "" {
		return false
	}
	if left == right {
		return true
	}
	shorter, longer := left, right
	if len(shorter) > len(longer) {
		shorter, longer = longer, shorter
	}
	return len(shorter) >= 12 && strings.Contains(longer, shorter)
}

func eventDirection(e models.Event) string {
	value := strings.ToLower(e.EventType + " " + e.RawData)
	if strings.Contains(value, "deassert") {
		return "deassert"
	}
	if strings.Contains(value, "assert") {
		return "assert"
	}
	return ""
}

func normalizeEventDescription(value string) string {
	value = strings.ToLower(value)
	value = strings.Map(func(r rune) rune {
		if unicode.IsLetter(r) || unicode.IsDigit(r) {
			return r
		}
		return ' '
	}, value)
	return strings.Join(strings.Fields(value), " ")
}

func sortInspurEvents(events []models.Event) {
	sort.SliceStable(events, func(i, j int) bool {
		left, right := events[i].Timestamp, events[j].Timestamp
		if left.IsZero() {
			return false
		}
		if right.IsZero() {
			return true
		}
		return left.Before(right)
	})
}

// buildSELDescription builds human-readable description
func buildSELDescription(eventDesc, status string) string {
	if status == "Asserted" || status == "Deasserted" {
		return eventDesc
	}
	return eventDesc + " (" + status + ")"
}