package pluginctl

import (
	"bytes"
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"text/template"

	"github.com/mattermost/mattermost/server/public/model"
)

const (
	// File permissions for generated directories and files.
	manifestDirPerm  = 0o750
	manifestFilePerm = 0o600

	// Name of the plugin manifest file.
	PluginManifestName = "plugin.json"
)

const pluginIDGoFileTemplate = `// This file is automatically generated. Do not modify it manually.

package main

import (
	"encoding/json"
	"strings"

	"github.com/mattermost/mattermost/server/public/model"
)

var manifest *model.Manifest

const manifestStr = ` + "`%s`" + `

func init() {
	_ = json.NewDecoder(strings.NewReader(manifestStr)).Decode(&manifest)
}
`

const pluginIDJSFileTemplate = `// This file is automatically generated. Do not modify it manually.

const manifest = JSON.parse(` + "`%s`" + `);

export default manifest;
`

// LoadPluginManifest loads and parses the plugin.json file from the current directory.
func LoadPluginManifest() (*model.Manifest, error) {
	return LoadPluginManifestFromPath(".")
}

// LoadPluginManifestFromPath loads and parses the plugin.json file from the specified directory.
func LoadPluginManifestFromPath(dir string) (*model.Manifest, error) {
	manifestPath := filepath.Join(dir, PluginManifestName)

	// Check if plugin.json exists
	if _, err := os.Stat(manifestPath); os.IsNotExist(err) {
		return nil, fmt.Errorf("plugin.json not found in directory %s", dir)
	}

	// Read the file
	data, err := os.ReadFile(manifestPath)
	if err != nil {
		return nil, fmt.Errorf("failed to read plugin.json: %w", err)
	}

	// Parse JSON into Manifest struct
	var manifest model.Manifest
	if err := json.Unmarshal(data, &manifest); err != nil {
		return nil, fmt.Errorf("failed to parse plugin.json: %w", err)
	}

	return &manifest, nil
}

// HasServerCode checks if the plugin contains server-side code.
func HasServerCode(manifest *model.Manifest) bool {
	return manifest.Server != nil && len(manifest.Server.Executables) > 0
}

// HasWebappCode checks if the plugin contains webapp code.
func HasWebappCode(manifest *model.Manifest) bool {
	return manifest.Webapp != nil && manifest.Webapp.BundlePath != ""
}

// applyManifest generates manifest files for server and webapp components.
func applyManifest(manifest *model.Manifest, pluginPath string) error {
	manifestBytes, err := json.Marshal(manifest)
	if err != nil {
		return fmt.Errorf("failed to marshal manifest: %w", err)
	}
	manifestStr := string(manifestBytes)

	// Generate server manifest file if server exists
	if HasServerCode(manifest) {
		serverDir := filepath.Join(pluginPath, "server")
		if err := os.MkdirAll(serverDir, manifestDirPerm); err != nil {
			return fmt.Errorf("failed to create server directory: %w", err)
		}

		serverManifestPath := filepath.Join(serverDir, "manifest.go")
		serverContent := fmt.Sprintf(pluginIDGoFileTemplate, manifestStr)

		if err := os.WriteFile(serverManifestPath, []byte(serverContent), manifestFilePerm); err != nil {
			return fmt.Errorf("failed to write server manifest: %w", err)
		}

		Logger.Info("Generated server manifest", "path", serverManifestPath)
	}

	// Generate webapp manifest file if webapp exists
	if HasWebappCode(manifest) {
		webappDir := filepath.Join(pluginPath, "webapp", "src")
		if err := os.MkdirAll(webappDir, manifestDirPerm); err != nil {
			return fmt.Errorf("failed to create webapp directory: %w", err)
		}

		webappManifestPath := filepath.Join(webappDir, "manifest.ts")
		webappContent := fmt.Sprintf(pluginIDJSFileTemplate, manifestStr)

		if err := os.WriteFile(webappManifestPath, []byte(webappContent), manifestFilePerm); err != nil {
			return fmt.Errorf("failed to write webapp manifest: %w", err)
		}

		Logger.Info("Generated webapp manifest", "path", webappManifestPath)
	}

	return nil
}

// RunManifestCommand implements the 'manifest' command functionality with subcommands.
func RunManifestCommand(args []string, pluginPath string) error {
	helpText := `Manage plugin manifest files

Usage:
  pluginctl manifest <subcommand> [options]

Subcommands:
  get TEMPLATE      Get manifest field using template syntax (e.g., {{.id}}, {{.version}})
  apply             Generate manifest files for server/webapp
  check             Validate plugin manifest

Options:
  --help, -h        Show this help message

Examples:
  pluginctl manifest get '{{.Id}}'           # Get plugin ID
  pluginctl manifest get '{{.Version}}'      # Get plugin version
  pluginctl manifest apply                   # Generate server/webapp manifest files
  pluginctl manifest check                   # Validate manifest`

	// Check for help flag
	if CheckForHelpFlag(args, helpText) {
		return nil
	}

	if len(args) == 0 {
		return ShowErrorWithHelp("manifest command requires a subcommand", helpText)
	}

	// Convert to absolute path
	absPath, err := filepath.Abs(pluginPath)
	if err != nil {
		return fmt.Errorf("failed to resolve path: %w", err)
	}

	// Load plugin manifest
	manifest, err := LoadPluginManifestFromPath(absPath)
	if err != nil {
		return fmt.Errorf("failed to load plugin manifest: %w", err)
	}

	subcommand := args[0]
	switch subcommand {
	case "get":
		if len(args) < 2 {
			return ShowErrorWithHelp("get subcommand requires a template expression", helpText)
		}
		templateStr := args[1]

		// Parse and execute template with manifest as context
		tmpl, err := template.New("manifest").Parse(templateStr)
		if err != nil {
			return fmt.Errorf("failed to parse template: %w", err)
		}

		var buf bytes.Buffer
		if err := tmpl.Execute(&buf, *manifest); err != nil {
			return fmt.Errorf("failed to execute template: %w", err)
		}

		fmt.Print(buf.String())
	case "apply":
		if err := applyManifest(manifest, absPath); err != nil {
			return fmt.Errorf("failed to apply manifest: %w", err)
		}
	case "check":
		if err := manifest.IsValid(); err != nil {
			Logger.Error("Plugin manifest validation failed", "error", err)

			return err
		}
		Logger.Info("Plugin manifest is valid")
	default:
		return ShowErrorWithHelp(fmt.Sprintf("unknown subcommand: %s", subcommand), helpText)
	}

	return nil
}

// WritePluginManifest saves the manifest to plugin.json in the specified path.
func WritePluginManifest(manifest *model.Manifest, path string) error {
	manifestPath := filepath.Join(path, PluginManifestName)

	// Marshal manifest to JSON with proper indentation
	data, err := json.MarshalIndent(manifest, "", "  ")
	if err != nil {
		return fmt.Errorf("failed to marshal manifest: %w", err)
	}

	// Write to file
	const fileMode = 0600
	if err := os.WriteFile(manifestPath, data, fileMode); err != nil {
		return fmt.Errorf("failed to write plugin.json: %w", err)
	}

	return nil
}