package gpu

import (
	"ffmpeg-gui/internal/ffmpeg"
	"log"
)

type GPUInfo struct {
	Name     string       `json:"name"`
	Vendor   string       `json:"vendor"`
	Encoders []EncoderCap `json:"encoders"`
}

type EncoderCap struct {
	Name      string `json:"name"`
	Codec     string `json:"codec"`
	Label     string `json:"label"`
	Available bool   `json:"available"`
}

type knownEnc struct{ Name, Vendor, Codec, Label string }

var allEncoders = []knownEnc{
	{"h264_nvenc", "nvidia", "h264", "H.264 NVENC"},
	{"hevc_nvenc", "nvidia", "hevc", "HEVC NVENC"},
	{"av1_nvenc", "nvidia", "av1", "AV1 NVENC"},
	{"h264_qsv", "intel", "h264", "H.264 QSV"},
	{"hevc_qsv", "intel", "hevc", "HEVC QSV"},
	{"av1_qsv", "intel", "av1", "AV1 QSV"},
	{"h264_amf", "amd", "h264", "H.264 AMF"},
	{"hevc_amf", "amd", "hevc", "HEVC AMF"},
	{"av1_amf", "amd", "av1", "AV1 AMF"},
}

var cpuEncoders = []knownEnc{
	{"libx264", "cpu", "h264", "H.264 (libx264)"},
	{"libx265", "cpu", "hevc", "H.265/HEVC (libx265)"},
	{"libsvtav1", "cpu", "av1", "AV1 (libsvtav1)"},
}

func DetectGPUs(exec *ffmpeg.Executor) []GPUInfo {
	// Step 1: Get GPU names (DXGI/Registry/PS — no ffmpeg needed)
	gpuNames := detectGPUNames()
	log.Printf("[gpu] names: %v", gpuNames)

	// Step 2: Detect encoder availability via ffmpeg (best effort)
	var encList string
	var ffmpegOK bool
	if exec != nil {
		out, err := exec.RunSync("-encoders")
		if err == nil {
			encList = out
			ffmpegOK = true
		} else {
			log.Printf("[gpu] ffmpeg -encoders failed: %v (showing GPUs without encoder info)", err)
		}
	}

	// Fall back to ffmpeg if no GPU names were found
	if len(gpuNames) == 0 && ffmpegOK {
		gpuNames = ffmpegFallback(exec)
	}
	if len(gpuNames) == 0 {
		gpuNames = []gpuName{{Name: "Unknown GPU", Vendor: "unknown"}}
	}

	// Build result
	var result []GPUInfo
	for _, gn := range gpuNames {
		result = append(result, GPUInfo{
			Name:     gn.Name,
			Vendor:   gn.Vendor,
			Encoders: capsForVendor(encList, gn.Vendor, ffmpegOK),
		})
	}

	// CPU
	cpuName := detectCPUName()
	log.Printf("[gpu] CPU: %s", cpuName)
	result = append(result, GPUInfo{
		Name:     cpuName,
		Vendor:   "cpu",
		Encoders: capsForVendor(encList, "cpu", ffmpegOK),
	})

	return result
}

func capsForVendor(encList, vendor string, ffmpegOK bool) []EncoderCap {
	var src []knownEnc
	switch vendor {
	case "cpu":
		src = cpuEncoders
	default:
		src = allEncoders
	}
	var caps []EncoderCap
	for _, ke := range src {
		if ke.Vendor == vendor || vendor == "cpu" {
			avail := ffmpegOK && containsWord(encList, ke.Name)
			if !ffmpegOK && vendor == "cpu" && ke.Name == "libx264" {
				avail = true // always assume x264 is available
			}
			caps = append(caps, EncoderCap{
				Name: ke.Name, Codec: ke.Codec, Label: ke.Label, Available: avail,
			})
		}
	}
	return caps
}

func ffmpegFallback(exec ffmpegExecutor) []gpuName {
	out, err := exec.RunSync("-encoders")
	if err != nil {
		return nil
	}
	var gpus []gpuName
	if wordIn(out, "h264_nvenc") || wordIn(out, "hevc_nvenc") {
		gpus = append(gpus, gpuName{Name: "NVIDIA GPU", Vendor: "nvidia"})
	}
	if wordIn(out, "h264_qsv") || wordIn(out, "hevc_qsv") {
		gpus = append(gpus, gpuName{Name: "Intel GPU", Vendor: "intel"})
	}
	if wordIn(out, "h264_amf") || wordIn(out, "hevc_amf") {
		gpus = append(gpus, gpuName{Name: "AMD GPU", Vendor: "amd"})
	}
	return gpus
}

type ffmpegExecutor interface {
	RunSync(args ...string) (string, error)
}

func containsWord(text, word string) bool {
	if len(word) == 0 || len(text) < len(word) {
		return false
	}
	for i := 0; i <= len(text)-len(word); i++ {
		if text[i:i+len(word)] == word {
			before := i == 0 || text[i-1] == ' ' || text[i-1] == '\n' || text[i-1] == '\r'
			after := i+len(word) >= len(text) || text[i+len(word)] == ' ' || text[i+len(word)] == '\n' || text[i+len(word)] == '\r'
			if before && after {
				return true
			}
		}
	}
	return false
}

func wordIn(text, word string) bool {
	return containsWord(text, word)
}