package infra

import (
	"context"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"
)

// MlEnvCheck holds the result of a single ML environment probe.
type MlEnvCheck struct {
	Name    string `json:"name"`              // e.g. "cuda_toolkit", "python_venv"
	Status  string `json:"status"`            // "ok" | "missing" | "warning" | "unknown"
	Version string `json:"version,omitempty"` // version string if detected
	Detail  string `json:"detail,omitempty"`  // human-readable extra info
}

// MlEnvReport is the full ML environment audit result.
type MlEnvReport struct {
	Gpus        []GpuInfo    `json:"gpus"`
	Checks      []MlEnvCheck `json:"checks"`
	OverallOK   bool         `json:"overall_ok"`
	GeneratedAt int64        `json:"generated_at"`
}

// AuditMlEnv probes the ML environment rooted at registryRoot.
// It checks for NVIDIA drivers, CUDA toolkit, Python venv, key Python
// packages and optional tools (sd, llama-cli) and a local vault path.
// Returns a non-nil MlEnvReport even when individual checks fail; the
// function itself only errors if a fundamental system call cannot be
// attempted.
func AuditMlEnv(registryRoot string) (MlEnvReport, error) {
	report := MlEnvReport{
		GeneratedAt: time.Now().Unix(),
	}

	// --- GPU detection (composes GetGpuInfo) ---
	gpus, err := GetGpuInfo()
	if err != nil {
		// Non-fatal: record absence.
		gpus = []GpuInfo{}
	}
	report.Gpus = gpus

	checks := []MlEnvCheck{}

	// --- nvidia-smi ---
	checks = append(checks, probeCommand("nvidia_smi", "nvidia-smi", []string{"--version"}, 5))

	// --- nvcc (CUDA toolkit compiler) ---
	nvcc := probeNvcc()
	checks = append(checks, nvcc)

	// --- Python venv ---
	venvCheck := probeVenv(registryRoot)
	checks = append(checks, venvCheck)

	// Python venv path for subsequent checks.
	venvPy := filepath.Join(registryRoot, "python", ".venv", "bin", "python3")

	// --- Python packages ---
	for _, pkg := range []string{"torch", "diffusers", "transformers", "huggingface_hub", "stable_diffusion_cpp_python"} {
		checks = append(checks, probePythonPackage(venvPy, pkg))
	}

	// --- sd.cpp CLI ---
	checks = append(checks, probeCommand("sd_cli", "sd", []string{"--version"}, 5))

	// --- llama.cpp CLI ---
	checks = append(checks, probeCommand("llama_cpp", "llama-cli", []string{"--version"}, 5))

	// --- imagegen_vault ---
	checks = append(checks, probeImagegenVault())

	report.Checks = checks

	// OverallOK: no "missing" checks (warning is tolerated) and at least 1 GPU.
	overallOK := len(gpus) > 0
	for _, c := range checks {
		if c.Status == "missing" {
			// stable_diffusion_cpp_python and sd_cli are optional — downgrade to warning-only.
			if c.Name == "stable_diffusion_cpp_python" || c.Name == "sd_cli" || c.Name == "llama_cpp" {
				continue
			}
			overallOK = false
		}
	}
	report.OverallOK = overallOK

	return report, nil
}

// probeCommand checks whether a binary is available in PATH by running it with
// the given args and recording any version output.
func probeCommand(name, binary string, args []string, timeoutSec int) MlEnvCheck {
	ctx, cancel := context.WithTimeout(context.Background(), time.Duration(timeoutSec)*time.Second)
	defer cancel()

	path, err := exec.LookPath(binary)
	if err != nil {
		return MlEnvCheck{Name: name, Status: "missing", Detail: fmt.Sprintf("%s not found in PATH", binary)}
	}

	out, err := exec.CommandContext(ctx, path, args...).CombinedOutput()
	version := strings.TrimSpace(string(out))
	if len(version) > 120 {
		version = version[:120]
	}
	if err != nil {
		return MlEnvCheck{Name: name, Status: "warning", Version: version, Detail: fmt.Sprintf("exit error: %v", err)}
	}
	return MlEnvCheck{Name: name, Status: "ok", Version: version}
}

// probeNvcc extracts the CUDA toolkit version from nvcc --version output.
func probeNvcc() MlEnvCheck {
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	path, err := exec.LookPath("nvcc")
	if err != nil {
		return MlEnvCheck{Name: "nvcc", Status: "missing", Detail: "nvcc not found in PATH (CUDA toolkit not installed)"}
	}

	out, err := exec.CommandContext(ctx, path, "--version").CombinedOutput()
	if err != nil {
		return MlEnvCheck{Name: "nvcc", Status: "warning", Detail: fmt.Sprintf("nvcc --version failed: %v", err)}
	}

	// Extract version from line like: "Cuda compilation tools, release 12.4, V12.4.99"
	version := ""
	for _, line := range strings.Split(string(out), "\n") {
		if strings.Contains(line, "release") {
			parts := strings.Split(line, ",")
			for _, p := range parts {
				p = strings.TrimSpace(p)
				if strings.HasPrefix(p, "release") {
					version = strings.TrimSpace(strings.TrimPrefix(p, "release"))
					break
				}
			}
			break
		}
	}
	if version == "" {
		version = strings.TrimSpace(string(out))
		if len(version) > 80 {
			version = version[:80]
		}
	}
	return MlEnvCheck{Name: "nvcc", Status: "ok", Version: version}
}

// probeVenv checks that the Python venv exists and is functional.
func probeVenv(registryRoot string) MlEnvCheck {
	py := filepath.Join(registryRoot, "python", ".venv", "bin", "python3")
	if _, err := os.Stat(py); os.IsNotExist(err) {
		return MlEnvCheck{Name: "python_venv", Status: "missing", Detail: fmt.Sprintf("not found: %s", py)}
	}

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	out, err := exec.CommandContext(ctx, py, "--version").CombinedOutput()
	version := strings.TrimSpace(string(out))
	if err != nil {
		return MlEnvCheck{Name: "python_venv", Status: "warning", Version: version, Detail: fmt.Sprintf("python3 --version failed: %v", err)}
	}
	return MlEnvCheck{Name: "python_venv", Status: "ok", Version: version}
}

// probePythonPackage imports a package in the venv Python and extracts __version__.
func probePythonPackage(venvPy, pkg string) MlEnvCheck {
	// Map package name → import name (for packages with different import names).
	importName := pkg
	switch pkg {
	case "stable_diffusion_cpp_python":
		importName = "stable_diffusion_cpp"
	case "huggingface_hub":
		importName = "huggingface_hub"
	}

	// Check that the venv python binary exists first.
	if _, err := os.Stat(venvPy); os.IsNotExist(err) {
		return MlEnvCheck{Name: pkg, Status: "unknown", Detail: "python_venv not available"}
	}

	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	script := fmt.Sprintf("import %s; v = getattr(%s, '__version__', None); print(v or 'unknown')", importName, importName)
	out, err := exec.CommandContext(ctx, venvPy, "-c", script).CombinedOutput()
	output := strings.TrimSpace(string(out))

	if err != nil {
		// Module not found → missing; other errors → warning.
		detail := output
		if len(detail) > 200 {
			detail = detail[:200]
		}
		if strings.Contains(output, "ModuleNotFoundError") || strings.Contains(output, "No module named") {
			return MlEnvCheck{Name: pkg, Status: "missing", Detail: fmt.Sprintf("%s not installed", importName)}
		}
		return MlEnvCheck{Name: pkg, Status: "warning", Detail: detail}
	}
	return MlEnvCheck{Name: pkg, Status: "ok", Version: output}
}

// probeImagegenVault checks that ~/vaults/imagegen_models exists and lists subdirs.
func probeImagegenVault() MlEnvCheck {
	home, err := os.UserHomeDir()
	if err != nil {
		return MlEnvCheck{Name: "imagegen_vault", Status: "unknown", Detail: "cannot determine home directory"}
	}
	vaultPath := filepath.Join(home, "vaults", "imagegen_models")
	entries, err := os.ReadDir(vaultPath)
	if os.IsNotExist(err) {
		return MlEnvCheck{Name: "imagegen_vault", Status: "missing", Detail: fmt.Sprintf("vault not found: %s", vaultPath)}
	}
	if err != nil {
		return MlEnvCheck{Name: "imagegen_vault", Status: "warning", Detail: fmt.Sprintf("cannot read vault: %v", err)}
	}

	subdirs := []string{}
	for _, e := range entries {
		if e.IsDir() {
			subdirs = append(subdirs, e.Name())
		}
	}
	detail := fmt.Sprintf("subdirs: %s", strings.Join(subdirs, ", "))
	if len(subdirs) == 0 {
		detail = "vault exists but is empty"
	}
	return MlEnvCheck{Name: "imagegen_vault", Status: "ok", Detail: detail}
}