package nvidia

import (
	"bufio"
	"regexp"
	"strings"

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

var (
	// Regex to extract GPU serial numbers from lspci output
	// Example: "	Capabilities: [2f0 v1] Device Serial Number 14-17-dc-65-77-2d-b0-48"
	gpuSerialRegex = regexp.MustCompile(`Device Serial Number\s+([\da-fA-F-]+)`)

	// Regex to extract PCI BDF from lspci header
	// Example: "2a:00.0 3D controller: NVIDIA Corporation Device 2335 (rev a1)"
	// Note: lspci format is bus:device.function (e.g., "2a:00.0")
	pciBDFRegex = regexp.MustCompile(`^([0-9a-fA-F]{2,4}:[0-9a-fA-F]{2}\.[0-9])\s+3D controller.*NVIDIA`)

	// Regex to extract devname mappings from fieldiag command line
	// Example: "devname=0000:ba:00.0,SXM5_SN_1653925027099"
	devnameRegex = regexp.MustCompile(`devname=([\da-fA-F:\.]+),(\w+)`)
)

// ParseInventoryLog parses inventory/output.log to extract GPU serial numbers
// from lspci output and map them to slots
func ParseInventoryLog(content []byte, result *models.AnalysisResult) error {
	if result.Hardware == nil || len(result.Hardware.GPUs) == 0 {
		// No GPUs to update
		return nil
	}

	scanner := bufio.NewScanner(strings.NewReader(string(content)))

	// First pass: build mapping of PCI BDF -> Slot name from fieldiag command line
	pciToSlot := make(map[string]string)
	for scanner.Scan() {
		line := scanner.Text()
		// Look for fieldiag command with devname parameters
		if strings.Contains(line, "devname=") && strings.Contains(line, "fieldiag") {
			matches := devnameRegex.FindAllStringSubmatch(line, -1)
			for _, match := range matches {
				if len(match) == 3 {
					pciBDF := match[1]
					slotName := match[2]
					// Extract slot number from name like "SXM5_SN_1653925027099"
					// We want to map to slot like "GPUSXM5"
					if strings.HasPrefix(slotName, "SXM") {
						parts := strings.Split(slotName, "_")
						if len(parts) >= 1 {
							// Convert "SXM5" to "GPUSXM5"
							slot := "GPU" + parts[0]
							pciToSlot[pciBDF] = slot
						}
					}
				}
			}
		}
	}

	// Second pass: extract GPU serial numbers from lspci output
	scanner = bufio.NewScanner(strings.NewReader(string(content)))
	var currentPCIBDF string
	var currentSlot string

	for scanner.Scan() {
		line := scanner.Text()

		// Check if this is a new GPU device header
		if match := pciBDFRegex.FindStringSubmatch(line); len(match) > 1 {
			currentPCIBDF = match[1]
			// Normalize BDF format - lspci uses short format (bus:device.function)
			// but fieldiag uses full format (domain:bus:device.function)
			// Convert "2a:00.0" to "0000:2a:00.0"
			normalizedBDF := currentPCIBDF
			if len(strings.Split(currentPCIBDF, ":")) == 2 {
				// Short format without domain, add 0000:
				normalizedBDF = "0000:" + currentPCIBDF
			}

			// Map to slot name if we have it
			if slot, ok := pciToSlot[normalizedBDF]; ok {
				currentSlot = slot
			} else if slot, ok := pciToSlot[currentPCIBDF]; ok {
				currentSlot = slot
			} else {
				currentSlot = ""
			}
			continue
		}

		// Look for Device Serial Number in capabilities
		if match := gpuSerialRegex.FindStringSubmatch(line); len(match) > 1 && currentSlot != "" {
			serialNumber := match[1]
			// Format: 14-17-dc-65-77-2d-b0-48
			// Convert to more readable format: 48:b0:2d:77:65:dc:17:14 (reversed)
			serialFormatted := formatGPUSerial(serialNumber)

			// Find the GPU in our results and update its serial number
			for i := range result.Hardware.GPUs {
				if result.Hardware.GPUs[i].Slot == currentSlot {
					result.Hardware.GPUs[i].SerialNumber = serialFormatted
					break
				}
			}
		}
	}

	return scanner.Err()
}

// formatGPUSerial formats GPU serial number from PCIe format to human-readable
// Input: "14-17-dc-65-77-2d-b0-48" (little-endian from PCIe)
// Output: "48:b0:2d:77:65:dc:17:14" (reversed to match GPU label)
func formatGPUSerial(serial string) string {
	parts := strings.Split(serial, "-")
	if len(parts) != 8 {
		return serial // Return as-is if unexpected format
	}

	// Reverse the bytes (PCIe reports in little-endian)
	reversed := make([]string, len(parts))
	for i := range parts {
		reversed[len(parts)-1-i] = strings.ToUpper(parts[i])
	}

	return strings.Join(reversed, ":")
}

// findInventoryOutputLog finds the inventory/output.log file
func findInventoryOutputLog(files []parser.ExtractedFile) *parser.ExtractedFile {
	for _, f := range files {
		// Look for inventory/output.log
		path := strings.ToLower(f.Path)
		if strings.Contains(path, "inventory/output.log") ||
			strings.Contains(path, "inventory\\output.log") {
			return &f
		}
	}
	return nil
}