package gpu

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

// GPUInfo holds detected GPU information.
type GPUInfo struct {
	Name     string       `json:"name"`
	Vendor   string       `json:"vendor"`
	Encoders []EncoderCap `json:"encoders"`
}

// EncoderCap describes an encoder capability.
type EncoderCap struct {
	Name      string `json:"name"`
	Codec     string `json:"codec"`
	Label     string `json:"label"`
	Available bool   `json:"available"`
}

// knownEncoders defines all known hardware encoders by vendor.
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"},
}

// DetectGPUs detects GPUs and their encoder capabilities.
// Uses a single ffmpeg -encoders call for speed.
func DetectGPUs(exec *ffmpeg.Executor) []GPUInfo {
	encList, err := exec.RunSync("-encoders")
	if err != nil {
		log.Printf("[gpu] ffmpeg -encoders failed: %v", err)
		return fallbackGPUs()
	}

	// Group encoders by vendor
	vendorEncs := map[string][]EncoderCap{}
	for _, ke := range allEncoders {
		available := containsWord(encList, ke.Name)
		vendorEncs[ke.Vendor] = append(vendorEncs[ke.Vendor], EncoderCap{
			Name: ke.Name, Codec: ke.Codec, Label: ke.Label, Available: available,
		})
	}

	// Get GPU names
	gpuNames := detectGPUNames()
	log.Printf("[gpu] detected GPU names: %v", gpuNames)

	if len(gpuNames) == 0 {
		gpuNames = []gpuName{{Name: "Unknown GPU", Vendor: "unknown"}}
	}

	var result []GPUInfo
	for _, gn := range gpuNames {
		encs := vendorEncs[gn.Vendor]
		if encs == nil {
			encs = []EncoderCap{}
		}
		result = append(result, GPUInfo{
			Name:     gn.Name,
			Vendor:   gn.Vendor,
			Encoders: encs,
		})
	}

	// Add CPU entry
	result = append(result, GPUInfo{
		Name:   "CPU",
		Vendor: "cpu",
		Encoders: []EncoderCap{
			{Name: "libx264", Codec: "h264", Label: "H.264 (libx264)", Available: containsWord(encList, "libx264")},
			{Name: "libx265", Codec: "hevc", Label: "H.265/HEVC (libx265)", Available: containsWord(encList, "libx265")},
			{Name: "libsvtav1", Codec: "av1", Label: "AV1 (libsvtav1)", Available: containsWord(encList, "libsvtav1")},
		},
	})

	log.Printf("[gpu] returning %d GPU entries", len(result))
	return result
}

func containsWord(text, word string) bool {
	// Simple substring match — the encoder list has one encoder per line
	return len(text) > 0 && len(word) > 0 && containsLine(text, word)
}

func containsLine(text, word string) bool {
	for i := 0; i < len(text); i++ {
		if i+len(word) > len(text) {
			break
		}
		if text[i:i+len(word)] == word {
			// Check word boundaries: should be preceded by space/newline and followed by space/newline
			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 fallbackGPUs() []GPUInfo {
	return []GPUInfo{
		{Name: "CPU", Vendor: "cpu", Encoders: []EncoderCap{
			{Name: "libx264", Codec: "h264", Label: "H.264 (libx264)", Available: true},
			{Name: "libx265", Codec: "hevc", Label: "H.265/HEVC (libx265)", Available: true},
		}},
	}
}