// ndpgen generates Navidrome Plugin Development Kit (PDK) code from annotated Go interfaces.
//
// This is the unified code generator that replaces hostgen and handles both host function
// wrappers and capability wrappers (when implemented).
//
// Usage:
//
//	ndpgen -input=./plugins/host -output=./plugins/pdk
//
// This generates code into language-specific subdirectories:
//   - Go:     $output/go/host/
//   - Python: $output/python/host/
//   - Rust:   $output/rust/host/
//
// Flags:
//
//	-input       Input directory containing Go source files with annotated interfaces
//	-output      Output directory base for generated files (default: same as input)
//	-package     Output package name for Go (default: host)
//	-host-only   Generate only host function wrappers (default: true, capability support TBD)
//	-go          Generate Go client wrappers (default: true when not using -python/-rust)
//	-python      Generate Python client wrappers (default: false)
//	-rust        Generate Rust client wrappers (default: false)
//	-v           Verbose output
//	-dry-run     Preview generated code without writing files
package main

import (
	"flag"
	"fmt"
	"go/format"
	"os"
	"path/filepath"
	"strings"

	"github.com/navidrome/navidrome/plugins/cmd/ndpgen/internal"
)

// config holds the parsed command-line configuration.
type config struct {
	inputDir         string
	outputDir        string // Base output directory (e.g., plugins/pdk)
	goOutputDir      string // Go output: $outputDir/go/host
	pythonOutputDir  string // Python output: $outputDir/python/host
	rustOutputDir    string // Rust output: $outputDir/rust/host
	pkgName          string
	hostOnly         bool
	generateGoClient bool
	generatePyClient bool
	generateRsClient bool
	verbose          bool
	dryRun           bool
}

func main() {
	cfg, err := parseConfig()
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
		os.Exit(1)
	}

	services, err := parseServices(cfg)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
		os.Exit(1)
	}
	if len(services) == 0 {
		return
	}

	if err := generateAllCode(cfg, services); err != nil {
		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
		os.Exit(1)
	}
}

// parseConfig parses command-line flags and returns the configuration.
func parseConfig() (*config, error) {
	var (
		inputDir  = flag.String("input", ".", "Input directory containing Go source files")
		outputDir = flag.String("output", "", "Base output directory for generated files (default: same as input)")
		pkgName   = flag.String("package", "host", "Output package name for Go (default: host)")
		hostOnly  = flag.Bool("host-only", true, "Generate only host function wrappers (capability support TBD)")
		goClient  = flag.Bool("go", false, "Generate Go client wrappers")
		pyClient  = flag.Bool("python", false, "Generate Python client wrappers")
		rsClient  = flag.Bool("rust", false, "Generate Rust client wrappers")
		verbose   = flag.Bool("v", false, "Verbose output")
		dryRun    = flag.Bool("dry-run", false, "Preview generated code without writing files")
	)
	flag.Parse()

	if *outputDir == "" {
		*outputDir = *inputDir
	}

	absInput, err := filepath.Abs(*inputDir)
	if err != nil {
		return nil, fmt.Errorf("resolving input path: %w", err)
	}
	absOutput, err := filepath.Abs(*outputDir)
	if err != nil {
		return nil, fmt.Errorf("resolving output path: %w", err)
	}

	// Set output directories for each language: $output/$lang/host/
	absGoOutput := filepath.Join(absOutput, "go", "host")
	absPythonOutput := filepath.Join(absOutput, "python", "host")
	absRustOutput := filepath.Join(absOutput, "rust", "host")

	// Determine what to generate
	// Default: generate Go clients if no language flag is specified
	anyLangFlag := *goClient || *pyClient || *rsClient

	return &config{
		inputDir:         absInput,
		outputDir:        absOutput,
		goOutputDir:      absGoOutput,
		pythonOutputDir:  absPythonOutput,
		rustOutputDir:    absRustOutput,
		pkgName:          *pkgName,
		hostOnly:         *hostOnly,
		generateGoClient: *goClient || !anyLangFlag,
		generatePyClient: *pyClient,
		generateRsClient: *rsClient,
		verbose:          *verbose,
		dryRun:           *dryRun,
	}, nil
}

// parseServices parses source files and returns discovered services.
func parseServices(cfg *config) ([]internal.Service, error) {
	if cfg.verbose {
		fmt.Printf("Input directory: %s\n", cfg.inputDir)
		fmt.Printf("Base output directory: %s\n", cfg.outputDir)
		if cfg.generateGoClient {
			fmt.Printf("Go output directory: %s\n", cfg.goOutputDir)
		}
		if cfg.generatePyClient {
			fmt.Printf("Python output directory: %s\n", cfg.pythonOutputDir)
		}
		if cfg.generateRsClient {
			fmt.Printf("Rust output directory: %s\n", cfg.rustOutputDir)
		}
		fmt.Printf("Package name: %s\n", cfg.pkgName)
		fmt.Printf("Host-only mode: %v\n", cfg.hostOnly)
		fmt.Printf("Generate Go client code: %v\n", cfg.generateGoClient)
		fmt.Printf("Generate Python client code: %v\n", cfg.generatePyClient)
		fmt.Printf("Generate Rust client code: %v\n", cfg.generateRsClient)
	}

	services, err := internal.ParseDirectory(cfg.inputDir)
	if err != nil {
		return nil, fmt.Errorf("parsing source files: %w", err)
	}

	if len(services) == 0 {
		if cfg.verbose {
			fmt.Println("No host services found")
		}
		return nil, nil
	}

	if cfg.verbose {
		fmt.Printf("Found %d host service(s)\n", len(services))
		for _, svc := range services {
			fmt.Printf("  - %s (%d methods)\n", svc.Name, len(svc.Methods))
		}
	}

	return services, nil
}

// generateAllCode generates all requested code for the services.
func generateAllCode(cfg *config, services []internal.Service) error {
	for _, svc := range services {
		if cfg.generateGoClient {
			if err := generateGoClientCode(svc, cfg.goOutputDir, cfg.pkgName, cfg.dryRun, cfg.verbose); err != nil {
				return fmt.Errorf("generating Go client code for %s: %w", svc.Name, err)
			}
		}
		if cfg.generatePyClient {
			if err := generatePythonClientCode(svc, cfg.pythonOutputDir, cfg.dryRun, cfg.verbose); err != nil {
				return fmt.Errorf("generating Python client code for %s: %w", svc.Name, err)
			}
		}
		if cfg.generateRsClient {
			if err := generateRustClientCode(svc, cfg.rustOutputDir, cfg.dryRun, cfg.verbose); err != nil {
				return fmt.Errorf("generating Rust client code for %s: %w", svc.Name, err)
			}
		}
	}

	if cfg.generateRsClient && len(services) > 0 {
		if err := generateRustLibFile(services, cfg.rustOutputDir, cfg.dryRun, cfg.verbose); err != nil {
			return fmt.Errorf("generating Rust lib.rs: %w", err)
		}
	}

	if cfg.generateGoClient && len(services) > 0 {
		if err := generateGoDocFile(services, cfg.goOutputDir, cfg.pkgName, cfg.dryRun, cfg.verbose); err != nil {
			return fmt.Errorf("generating Go doc.go: %w", err)
		}
		if err := generateGoModFile(cfg.goOutputDir, cfg.dryRun, cfg.verbose); err != nil {
			return fmt.Errorf("generating Go go.mod: %w", err)
		}
	}

	return nil
}

// generateGoClientCode generates Go client-side code for a service.
func generateGoClientCode(svc internal.Service, outputDir, pkgName string, dryRun, verbose bool) error {
	code, err := internal.GenerateClientGo(svc, pkgName)
	if err != nil {
		return fmt.Errorf("generating code: %w", err)
	}

	formatted, err := format.Source(code)
	if err != nil {
		return fmt.Errorf("formatting code: %w\nRaw code:\n%s", err, code)
	}

	// Client code goes directly in the output directory
	clientFile := filepath.Join(outputDir, "nd_host_"+strings.ToLower(svc.Name)+".go")

	if dryRun {
		fmt.Printf("=== %s ===\n%s\n", clientFile, formatted)
	} else {
		// Create output directory if needed
		if err := os.MkdirAll(outputDir, 0755); err != nil {
			return fmt.Errorf("creating output directory: %w", err)
		}

		if err := os.WriteFile(clientFile, formatted, 0600); err != nil {
			return fmt.Errorf("writing file: %w", err)
		}

		if verbose {
			fmt.Printf("Generated Go client code: %s\n", clientFile)
		}
	}

	// Also generate stub file for non-WASM platforms
	return generateGoClientStubCode(svc, outputDir, pkgName, dryRun, verbose)
}

// generateGoClientStubCode generates stub code for non-WASM platforms.
func generateGoClientStubCode(svc internal.Service, outputDir, pkgName string, dryRun, verbose bool) error {
	code, err := internal.GenerateClientGoStub(svc, pkgName)
	if err != nil {
		return fmt.Errorf("generating stub code: %w", err)
	}

	formatted, err := format.Source(code)
	if err != nil {
		return fmt.Errorf("formatting stub code: %w\nRaw code:\n%s", err, code)
	}

	// Stub code goes directly in output directory with _stub suffix
	stubFile := filepath.Join(outputDir, "nd_host_"+strings.ToLower(svc.Name)+"_stub.go")

	if dryRun {
		fmt.Printf("=== %s ===\n%s\n", stubFile, formatted)
		return nil
	}

	// Create output directory if needed
	if err := os.MkdirAll(outputDir, 0755); err != nil {
		return fmt.Errorf("creating output directory: %w", err)
	}

	if err := os.WriteFile(stubFile, formatted, 0600); err != nil {
		return fmt.Errorf("writing stub file: %w", err)
	}

	if verbose {
		fmt.Printf("Generated Go client stub: %s\n", stubFile)
	}
	return nil
}

// generatePythonClientCode generates Python client-side code for a service.
func generatePythonClientCode(svc internal.Service, outputDir string, dryRun, verbose bool) error {
	code, err := internal.GenerateClientPython(svc)
	if err != nil {
		return fmt.Errorf("generating code: %w", err)
	}

	// Python code goes directly in the output directory
	clientFile := filepath.Join(outputDir, "nd_host_"+strings.ToLower(svc.Name)+".py")

	if dryRun {
		fmt.Printf("=== %s ===\n%s\n", clientFile, code)
		return nil
	}

	// Create output directory if needed
	if err := os.MkdirAll(outputDir, 0755); err != nil {
		return fmt.Errorf("creating python client directory: %w", err)
	}

	if err := os.WriteFile(clientFile, code, 0600); err != nil {
		return fmt.Errorf("writing file: %w", err)
	}

	if verbose {
		fmt.Printf("Generated Python client code: %s\n", clientFile)
	}
	return nil
}

// generateRustClientCode generates Rust client-side code for a service.
func generateRustClientCode(svc internal.Service, outputDir string, dryRun, verbose bool) error {
	code, err := internal.GenerateClientRust(svc)
	if err != nil {
		return fmt.Errorf("generating code: %w", err)
	}

	// Rust code goes directly in the output directory
	clientFile := filepath.Join(outputDir, "nd_host_"+strings.ToLower(svc.Name)+".rs")

	if dryRun {
		fmt.Printf("=== %s ===\n%s\n", clientFile, code)
		return nil
	}

	// Create output directory if needed
	if err := os.MkdirAll(outputDir, 0755); err != nil {
		return fmt.Errorf("creating rust client directory: %w", err)
	}

	if err := os.WriteFile(clientFile, code, 0600); err != nil {
		return fmt.Errorf("writing file: %w", err)
	}

	if verbose {
		fmt.Printf("Generated Rust client code: %s\n", clientFile)
	}
	return nil
}

// generateRustLibFile generates the lib.rs file that exposes all Rust modules.
func generateRustLibFile(services []internal.Service, outputDir string, dryRun, verbose bool) error {
	code, err := internal.GenerateRustLib(services)
	if err != nil {
		return fmt.Errorf("generating lib.rs: %w", err)
	}

	// lib.rs goes directly in the output directory
	libFile := filepath.Join(outputDir, "lib.rs")

	if dryRun {
		fmt.Printf("=== %s ===\n%s\n", libFile, code)
		return nil
	}

	// Create output directory if needed
	if err := os.MkdirAll(outputDir, 0755); err != nil {
		return fmt.Errorf("creating rust client directory: %w", err)
	}

	if err := os.WriteFile(libFile, code, 0600); err != nil {
		return fmt.Errorf("writing file: %w", err)
	}

	if verbose {
		fmt.Printf("Generated Rust lib.rs: %s\n", libFile)
	}
	return nil
}

// generateGoDocFile generates the doc.go file for the Go library.
func generateGoDocFile(services []internal.Service, outputDir, pkgName string, dryRun, verbose bool) error {
	code, err := internal.GenerateGoDoc(services, pkgName)
	if err != nil {
		return fmt.Errorf("generating doc.go: %w", err)
	}

	formatted, err := format.Source(code)
	if err != nil {
		return fmt.Errorf("formatting doc.go: %w\nRaw code:\n%s", err, code)
	}

	docFile := filepath.Join(outputDir, "doc.go")

	if dryRun {
		fmt.Printf("=== %s ===\n%s\n", docFile, formatted)
		return nil
	}

	// Create output directory if needed
	if err := os.MkdirAll(outputDir, 0755); err != nil {
		return fmt.Errorf("creating output directory: %w", err)
	}

	if err := os.WriteFile(docFile, formatted, 0600); err != nil {
		return fmt.Errorf("writing file: %w", err)
	}

	if verbose {
		fmt.Printf("Generated Go doc.go: %s\n", docFile)
	}
	return nil
}

// generateGoModFile generates the go.mod file for the Go library.
func generateGoModFile(outputDir string, dryRun, verbose bool) error {
	code, err := internal.GenerateGoMod()
	if err != nil {
		return fmt.Errorf("generating go.mod: %w", err)
	}

	modFile := filepath.Join(outputDir, "go.mod")

	if dryRun {
		fmt.Printf("=== %s ===\n%s\n", modFile, code)
		return nil
	}

	// Create output directory if needed
	if err := os.MkdirAll(outputDir, 0755); err != nil {
		return fmt.Errorf("creating output directory: %w", err)
	}

	if err := os.WriteFile(modFile, code, 0600); err != nil {
		return fmt.Errorf("writing file: %w", err)
	}

	if verbose {
		fmt.Printf("Generated Go go.mod: %s\n", modFile)
	}
	return nil
}