// Package blender handles Blender binary management and execution.
package blender

import (
	"fmt"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"strings"

	"jiggablend/internal/runner/api"
	"jiggablend/internal/runner/workspace"
)

// Manager handles Blender binary downloads and management.
type Manager struct {
	manager      *api.ManagerClient
	workspaceDir string
}

// NewManager creates a new Blender manager.
func NewManager(managerClient *api.ManagerClient, workspaceDir string) *Manager {
	return &Manager{
		manager:      managerClient,
		workspaceDir: workspaceDir,
	}
}

// GetBinaryPath returns the path to the Blender binary for a specific version.
// Downloads from manager and extracts if not already present.
func (m *Manager) GetBinaryPath(version string) (string, error) {
	blenderDir := filepath.Join(m.workspaceDir, "blender-versions")
	if err := os.MkdirAll(blenderDir, 0755); err != nil {
		return "", fmt.Errorf("failed to create blender directory: %w", err)
	}

	// Check if already installed - look for version folder first
	versionDir := filepath.Join(blenderDir, version)
	binaryPath := filepath.Join(versionDir, "blender")

	// Check if version folder exists and contains the binary
	if versionInfo, err := os.Stat(versionDir); err == nil && versionInfo.IsDir() {
		// Version folder exists, check if binary is present
		if binaryInfo, err := os.Stat(binaryPath); err == nil {
			// Verify it's actually a file (not a directory)
			if !binaryInfo.IsDir() {
				absBinaryPath, err := ResolveBinaryPath(binaryPath)
				if err != nil {
					return "", err
				}
				log.Printf("Found existing Blender %s installation at %s", version, absBinaryPath)
				return absBinaryPath, nil
			}
		}
		// Version folder exists but binary is missing - might be incomplete installation
		log.Printf("Version folder %s exists but binary not found, will re-download", versionDir)
	}

	// Download from manager
	log.Printf("Downloading Blender %s from manager", version)

	reader, err := m.manager.DownloadBlender(version)
	if err != nil {
		return "", err
	}
	defer reader.Close()

	// Manager serves pre-decompressed .tar files - extract directly
	log.Printf("Extracting Blender %s...", version)
	if err := workspace.ExtractTarStripPrefix(reader, versionDir); err != nil {
		return "", fmt.Errorf("failed to extract blender: %w", err)
	}

	// Verify binary exists
	if _, err := os.Stat(binaryPath); err != nil {
		return "", fmt.Errorf("blender binary not found after extraction")
	}

	absBinaryPath, err := ResolveBinaryPath(binaryPath)
	if err != nil {
		return "", err
	}

	log.Printf("Blender %s installed at %s", version, absBinaryPath)
	return absBinaryPath, nil
}

// GetBinaryForJob returns the Blender binary path for a job.
// Uses the version from metadata or falls back to system blender.
func (m *Manager) GetBinaryForJob(version string) (string, error) {
	if version == "" {
		return ResolveBinaryPath("blender")
	}

	return m.GetBinaryPath(version)
}

// ResolveBinaryPath resolves a Blender executable to an absolute path.
func ResolveBinaryPath(blenderBinary string) (string, error) {
	if blenderBinary == "" {
		return "", fmt.Errorf("blender binary path is empty")
	}

	if strings.Contains(blenderBinary, string(filepath.Separator)) {
		absPath, err := filepath.Abs(blenderBinary)
		if err != nil {
			return "", fmt.Errorf("failed to resolve blender binary path %q: %w", blenderBinary, err)
		}
		return absPath, nil
	}

	resolvedPath, err := exec.LookPath(blenderBinary)
	if err != nil {
		return "", fmt.Errorf("failed to locate blender binary %q in PATH: %w", blenderBinary, err)
	}
	absPath, err := filepath.Abs(resolvedPath)
	if err != nil {
		return "", fmt.Errorf("failed to resolve blender binary path %q: %w", resolvedPath, err)
	}
	return absPath, nil
}

// TarballEnv returns a copy of baseEnv with LD_LIBRARY_PATH set so that a
// tarball Blender installation can find its bundled libs (e.g. lib/python3.x).
// If blenderBinary is the system "blender" or has no path component, baseEnv is
// returned unchanged.
func TarballEnv(blenderBinary string, baseEnv []string) []string {
	if blenderBinary == "" || blenderBinary == "blender" {
		return baseEnv
	}
	if !strings.Contains(blenderBinary, string(os.PathSeparator)) {
		return baseEnv
	}
	blenderDir := filepath.Dir(blenderBinary)
	libDir := filepath.Join(blenderDir, "lib")
	ldLib := libDir
	for _, e := range baseEnv {
		if strings.HasPrefix(e, "LD_LIBRARY_PATH=") {
			existing := strings.TrimPrefix(e, "LD_LIBRARY_PATH=")
			if existing != "" {
				ldLib = libDir + ":" + existing
			}
			break
		}
	}
	out := make([]string, 0, len(baseEnv)+1)
	done := false
	for _, e := range baseEnv {
		if strings.HasPrefix(e, "LD_LIBRARY_PATH=") {
			out = append(out, "LD_LIBRARY_PATH="+ldLib)
			done = true
			continue
		}
		out = append(out, e)
	}
	if !done {
		out = append(out, "LD_LIBRARY_PATH="+ldLib)
	}
	return out
}