package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"os"
	"path/filepath"
	"text/tabwriter"
)

func main() {
	home, err := os.UserHomeDir()
	if err != nil {
		log.Fatalf("Could not locate user home dir: %v", err)
	}

	defaultConfigPath := filepath.Join(home, ".config", "vssm", "config.json")

	configFlag := flag.String("config", defaultConfigPath, "Explicit path targeting a custom vssm config.json profile")

	flag.Usage = printUsage
	flag.Parse()

	args := flag.Args()
	if len(args) < 1 {
		printUsage()
		return
	}

	absConfigPath, err := filepath.Abs(*configFlag)
	if err != nil {
		log.Fatalf("Failed to resolve absolute configuration path target: %v", err)
	}

	cfg, err := LoadOrCreateConfig(absConfigPath)
	if err != nil {
		log.Fatalf("Initialization failed: %v", err)
	}

	subCommand := args[0]

	switch subCommand {

	case "daemon":
		fmt.Printf("Initializing VS server manager background supervisor [Config: %s]...\n", absConfigPath)
		if err := StartDaemon(cfg, absConfigPath); err != nil {
			log.Fatalf("Daemon runtime fatal error: %v", err)
		}

	case "create":
		if len(args) < 3 {
			log.Fatalf("Usage: vssm create <instance_name> <version>")
		}
		name := args[1]
		version := args[2]
		sendIPCRequest(cfg, "POST", fmt.Sprintf("/instances/create?name=%s&version=%s", url.QueryEscape(name), url.QueryEscape(version)), nil)

	case "start":
		if len(args) < 2 {
			log.Fatalf("Usage: vssm start <instance_name>")
		}
		name := args[1]
		sendIPCRequest(cfg, "POST", fmt.Sprintf("/instances/start?name=%s", url.QueryEscape(name)), nil)

	case "stop":
		if len(args) < 2 {
			log.Fatalf("Usage: vssm stop <instance_name>")
		}
		name := args[1]
		sendIPCRequest(cfg, "POST", fmt.Sprintf("/instances/stop?name=%s", url.QueryEscape(name)), nil)

	case "cmd":
		if len(args) < 3 {
			log.Fatalf("Usage: vssm cmd <instance_name> \"<server command>\"")
		}
		name := args[1]
		serverCmd := args[2]

		payload := CommandPayload{Command: serverCmd}
		body, _ := json.Marshal(payload)
		sendIPCRequest(cfg, "POST", fmt.Sprintf("/instances/command?name=%s", url.QueryEscape(name)), bytes.NewBuffer(body))

	case "list", "status":
		fetchAndPrintStatus(cfg)

	case "show-config":
		fmt.Printf("%v", cfg.Storage.AppDataDir)

	default:
		printUsage()
	}
}

func sendIPCRequest(cfg *AppConfig, method string, path string, body io.Reader) {
	targetUrl := fmt.Sprintf("http://%s%s", cfg.Daemon.ListenAddress, path)
	req, err := http.NewRequest(method, targetUrl, body)
	if err != nil {
		log.Fatalf("Failed to construct IPC frame: %v", err)
	}

	if body != nil {
		req.Header.Set("Content-Type", "application/json")
	}

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		log.Fatalf("IPC connection failed. Is the vs-manager daemon running? Error: %v", err)
	}
	defer resp.Body.Close()

	respBody, _ := io.ReadAll(resp.Body)

	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusCreated {
		log.Fatalf("Error from daemon: %s", string(respBody))
	}

	fmt.Println(string(respBody))
}

func fetchAndPrintStatus(cfg *AppConfig) {
	targetUrl := fmt.Sprintf("http://%s/instances/list", cfg.Daemon.ListenAddress)
	resp, err := http.Get(targetUrl)
	if err != nil {
		log.Fatalf("IPC connection failed. Is the vs-manager daemon running? Error: %v", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		respBody, _ := io.ReadAll(resp.Body)
		log.Fatalf("Error from daemon: %s", string(respBody))
	}

	var instances []InstanceStatusResponse
	if err := json.NewDecoder(resp.Body).Decode(&instances); err != nil {
		log.Fatalf("Failed to decode daemon status matrix: %v", err)
	}

	if len(instances) == 0 {
		fmt.Println("No instances configured yet. Use 'create' to provision one.")
		return
	}

	w := tabwriter.NewWriter(os.Stdout, 0, 0, 3, ' ', 0)
	fmt.Fprintln(w, "INSTANCE NAME\tVERSION\tPORT\tSTATUS")
	fmt.Fprintln(w, "-------------\t-------\t----\t------")

	for _, inst := range instances {
		fmt.Fprintf(w, "%s\t%s\t%d\t%s\n", inst.Name, inst.Version, inst.Port, inst.Status)
	}
	w.Flush()
}

func printUsage() {
	fmt.Println("VintageStory Server Manager")
	fmt.Println("\nGlobal Options:")
	fmt.Println("  --config <path>                  Explicitly target a non-default config structure file location")
	fmt.Println("\nUsage Commands:")
	fmt.Println("  vssm daemon                      Starts the background process supervisor")
	fmt.Println("  vssm create <name> <version>     Provisions baseline configuration and stores instance profile")
	fmt.Println("  vssm start <name>                Launches an existing server instance using stored profile")
	fmt.Println("  vssm stop <name>                 Gracefully shuts down a server instance")
	fmt.Println("  vssm cmd <name> \"<command>\"    Dispatches a terminal console command down the pipe")
	fmt.Println("  vssm list                        Displays the operational matrix of all instances")
}