// kvs-shell/main.go
package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
	"strings"
	"time"

	"github.com/chzyer/readline"
	"github.com/fatih/color"
)

// Types matching your backend
type StoredValue struct {
	UUID      string          `json:"uuid"`
	Timestamp int64           `json:"timestamp"`
	Data      json.RawMessage `json:"data"`
}

type Member struct {
	ID              string `json:"id"`
	Address         string `json:"address"`
	LastSeen        int64  `json:"last_seen"`
	JoinedTimestamp int64  `json:"joined_timestamp"`
}

type User struct {
	UUID         string   `json:"uuid"`
	NicknameHash string   `json:"nickname_hash"`
	Groups       []string `json:"groups"`
	CreatedAt    int64    `json:"created_at"`
	UpdatedAt    int64    `json:"updated_at"`
}

type Group struct {
	UUID      string   `json:"uuid"`
	NameHash  string   `json:"name_hash"`
	Members   []string `json:"members"`
	CreatedAt int64    `json:"created_at"`
	UpdatedAt int64    `json:"updated_at"`
}

// Client state
type KVSClient struct {
	baseURL       string
	currentToken  string
	currentUser   string
	httpClient    *http.Client
	profiles      map[string]Profile // Stored user profiles
	activeProfile string
}

type Profile struct {
	Name     string `json:"name"`
	Token    string `json:"token"`
	UserUUID string `json:"user_uuid"`
	BaseURL  string `json:"base_url"`
}

// Colors
var (
	cyan    = color.New(color.FgCyan).SprintFunc()
	green   = color.New(color.FgGreen).SprintFunc()
	yellow  = color.New(color.FgYellow).SprintFunc()
	red     = color.New(color.FgRed).SprintFunc()
	magenta = color.New(color.FgMagenta).SprintFunc()
)

func NewKVSClient(baseURL string) *KVSClient {
	return &KVSClient{
		baseURL: baseURL,
		httpClient: &http.Client{
			Timeout: 30 * time.Second,
		},
		profiles: make(map[string]Profile),
	}
}

// HTTP request helper
func (c *KVSClient) doRequest(method, path string, body interface{}) ([]byte, int, error) {
	var reqBody io.Reader
	if body != nil {
		jsonData, err := json.Marshal(body)
		if err != nil {
			return nil, 0, err
		}
		reqBody = bytes.NewBuffer(jsonData)
	}

	req, err := http.NewRequest(method, c.baseURL+path, reqBody)
	if err != nil {
		return nil, 0, err
	}

	req.Header.Set("Content-Type", "application/json")
	if c.currentToken != "" {
		req.Header.Set("Authorization", "Bearer "+c.currentToken)
	}

	resp, err := c.httpClient.Do(req)
	if err != nil {
		return nil, 0, err
	}
	defer resp.Body.Close()

	respBody, err := io.ReadAll(resp.Body)
	return respBody, resp.StatusCode, err
}

// Command handlers
func (c *KVSClient) handleConnect(args []string) {
	if len(args) < 1 {
		fmt.Println(red("Usage: connect <base-url>"))
		return
	}
	c.baseURL = args[0]
	fmt.Println(green("Connected to:"), c.baseURL)
}

func (c *KVSClient) handleAuth(args []string) {
	if len(args) < 1 {
		fmt.Println(red("Usage: auth <token>"))
		return
	}
	c.currentToken = args[0]
	fmt.Println(green("Authentication token set"))
}

func (c *KVSClient) handleProfile(args []string) {
	if len(args) == 0 {
		// List profiles
		if len(c.profiles) == 0 {
			fmt.Println(yellow("No profiles configured"))
			return
		}
		fmt.Println(cyan("Available profiles:"))
		for name, profile := range c.profiles {
			marker := " "
			if name == c.activeProfile {
				marker = "*"
			}
			fmt.Printf("%s %s (user: %s, url: %s)\n", marker, name, profile.UserUUID, profile.BaseURL)
		}
		return
	}

	subCmd := args[0]
	switch subCmd {
	case "add":
		if len(args) < 4 {
			fmt.Println(red("Usage: profile add <name> <token> <user-uuid> [base-url]"))
			return
		}
		baseURL := c.baseURL
		if len(args) >= 5 {
			baseURL = args[4]
		}
		c.profiles[args[1]] = Profile{
			Name:     args[1],
			Token:    args[2],
			UserUUID: args[3],
			BaseURL:  baseURL,
		}
		fmt.Println(green("Profile added:"), args[1])

	case "use":
		if len(args) < 2 {
			fmt.Println(red("Usage: profile use <name>"))
			return
		}
		profile, ok := c.profiles[args[1]]
		if !ok {
			fmt.Println(red("Profile not found:"), args[1])
			return
		}
		c.currentToken = profile.Token
		c.currentUser = profile.UserUUID
		c.baseURL = profile.BaseURL
		c.activeProfile = args[1]
		fmt.Println(green("Switched to profile:"), args[1])

	case "remove":
		if len(args) < 2 {
			fmt.Println(red("Usage: profile remove <name>"))
			return
		}
		delete(c.profiles, args[1])
		if c.activeProfile == args[1] {
			c.activeProfile = ""
		}
		fmt.Println(green("Profile removed:"), args[1])
	}
}

func (c *KVSClient) handleGet(args []string) {
	if len(args) < 1 {
		fmt.Println(red("Usage: get <key>"))
		return
	}

	respBody, status, err := c.doRequest("GET", "/kv/"+args[0], nil)
	if err != nil {
		fmt.Println(red("Error:"), err)
		return
	}

	if status == 404 {
		fmt.Println(yellow("Key not found"))
		return
	}

	if status != 200 {
		fmt.Println(red("Error:"), string(respBody))
		return
	}

	var stored StoredValue
	if err := json.Unmarshal(respBody, &stored); err != nil {
		fmt.Println(red("Error parsing response:"), err)
		return
	}

	fmt.Println(cyan("UUID:     "), stored.UUID)
	fmt.Println(cyan("Timestamp:"), time.UnixMilli(stored.Timestamp).Format(time.RFC3339))
	fmt.Println(cyan("Data:"))
	
	var pretty bytes.Buffer
	json.Indent(&pretty, stored.Data, "", "  ")
	fmt.Println(pretty.String())
}

func (c *KVSClient) handlePut(args []string) {
	if len(args) < 2 {
		fmt.Println(red("Usage: put <key> <json-data>"))
		return
	}

	// Parse JSON data
	var data json.RawMessage
	if err := json.Unmarshal([]byte(args[1]), &data); err != nil {
		printJSONError(args[1], err)
		return
	}

	respBody, status, err := c.doRequest("PUT", "/kv/"+args[0], data)
	if err != nil {
		fmt.Println(red("Error:"), err)
		return
	}

	if status != 200 && status != 201 {
		fmt.Println(red("Error:"), string(respBody))
		return
	}

	type PutResponse struct {
		UUID      string `json:"uuid"`
		Timestamp int64  `json:"timestamp"`
	}

	var resp PutResponse
	if err := json.Unmarshal(respBody, &resp); err == nil {
		fmt.Println(green("Stored successfully"))
		fmt.Println(cyan("UUID:     "), resp.UUID)
		fmt.Println(cyan("Timestamp:"), time.UnixMilli(resp.Timestamp).Format(time.RFC3339))
	}
}

func (c *KVSClient) handleDelete(args []string) {
	if len(args) < 1 {
		fmt.Println(red("Usage: delete <key>"))
		return
	}

	_, status, err := c.doRequest("DELETE", "/kv/"+args[0], nil)
	if err != nil {
		fmt.Println(red("Error:"), err)
		return
	}

	if status == 404 {
		fmt.Println(yellow("Key not found"))
		return
	}

	if status == 204 {
		fmt.Println(green("Deleted successfully"))
	} else {
		fmt.Println(red("Unexpected status:"), status)
	}
}

func (c *KVSClient) handleMembers(args []string) {
	respBody, status, err := c.doRequest("GET", "/members/", nil)
	if err != nil {
		fmt.Println(red("Error:"), err)
		return
	}

	if status != 200 {
		fmt.Println(red("Error:"), string(respBody))
		return
	}

	var members []Member
	if err := json.Unmarshal(respBody, &members); err != nil {
		fmt.Println(red("Error parsing response:"), err)
		return
	}

	if len(members) == 0 {
		fmt.Println(yellow("No cluster members"))
		return
	}

	fmt.Println(cyan("Cluster Members:"))
	for _, m := range members {
		lastSeen := time.UnixMilli(m.LastSeen).Format(time.RFC3339)
		fmt.Printf("  • %s (%s) - Last seen: %s\n", m.ID, m.Address, lastSeen)
	}
}

func (c *KVSClient) handleHealth(args []string) {
	respBody, status, err := c.doRequest("GET", "/health", nil)
	if err != nil {
		fmt.Println(red("Error:"), err)
		return
	}

	if status != 200 {
		fmt.Println(red("Service unhealthy"))
		return
	}

	var health map[string]interface{}
	if err := json.Unmarshal(respBody, &health); err != nil {
		fmt.Println(red("Error parsing response:"), err)
		return
	}

	fmt.Println(green("Service Status:"))
	for k, v := range health {
		fmt.Printf("  %s: %v\n", cyan(k), v)
	}
}

func (c *KVSClient) handleUserList(args []string) {
	// Note: Backend doesn't have a list-all endpoint, this would need to be added
	fmt.Println(yellow("User listing not implemented in backend API"))
}

func (c *KVSClient) handleUserGet(args []string) {
	if len(args) < 1 {
		fmt.Println(red("Usage: user get <uuid>"))
		return
	}

	respBody, status, err := c.doRequest("GET", "/api/users/"+args[0], nil)
	if err != nil {
		fmt.Println(red("Error:"), err)
		return
	}

	if status == 404 {
		fmt.Println(yellow("User not found"))
		return
	}

	if status != 200 {
		fmt.Println(red("Error:"), string(respBody))
		return
	}

	var user User
	if err := json.Unmarshal(respBody, &user); err != nil {
		fmt.Println(red("Error parsing response:"), err)
		return
	}

	fmt.Println(cyan("User Details:"))
	fmt.Printf("  UUID:          %s\n", user.UUID)
	fmt.Printf("  Nickname Hash: %s\n", user.NicknameHash)
	fmt.Printf("  Groups:        %v\n", user.Groups)
	fmt.Printf("  Created:       %s\n", time.Unix(user.CreatedAt, 0).Format(time.RFC3339))
	fmt.Printf("  Updated:       %s\n", time.Unix(user.UpdatedAt, 0).Format(time.RFC3339))
}

// printJSONError displays a user-friendly JSON parsing error with helpful hints
func printJSONError(input string, err error) {
	fmt.Println(red("❌ Invalid JSON:"), err)
	fmt.Println()

	// Show what was received
	if len(input) > 100 {
		fmt.Println(yellow("Received:"), input[:100]+"...")
	} else {
		fmt.Println(yellow("Received:"), input)
	}
	fmt.Println()

	// Provide helpful hints based on common errors
	errMsg := err.Error()

	if strings.Contains(errMsg, "looking for beginning of") ||
	   strings.Contains(errMsg, "invalid character") {
		fmt.Println(cyan("💡 Tip:"), "JSON with spaces needs quotes:")
		fmt.Println(green("  ✓ Correct:"), "put key '{\"hello\":\"world\"}'")
		fmt.Println(green("  ✓ Correct:"), "put key '{\"a\":1,\"b\":2}'")
		fmt.Println(green("  ✓ Compact:"), "put key {\"a\":1,\"b\":2}  (no spaces)")
		fmt.Println(red("  ✗ Wrong:  "), "put key {\"a\": 1, \"b\": 2}  (spaces without quotes)")
	} else if strings.Contains(errMsg, "unexpected end of JSON") {
		fmt.Println(cyan("💡 Tip:"), "JSON appears incomplete or cut off")
		fmt.Println(green("  Check:"), "Are all brackets/braces matched? {}, []")
		fmt.Println(green("  Check:"), "Did spaces split your JSON into multiple arguments?")
	} else {
		fmt.Println(cyan("💡 Tip:"), "Wrap JSON in quotes for complex values:")
		fmt.Println(green("  Single quotes:"), "put key '{\"your\":\"json\"}'")
		fmt.Println(green("  Double quotes:"), "put key \"{\\\"your\\\":\\\"json\\\"}\"")
	}
}

func (c *KVSClient) handleHelp(args []string) {
	help := `
KVS Interactive Shell - Available Commands:

Connection & Authentication:
  connect <url>              - Connect to KVS server
  auth <token>               - Set authentication token
  profile add <name> <token> <user-uuid> [url] - Add user profile
  profile use <name>         - Switch to user profile
  profile remove <name>      - Remove user profile
  profile                    - List all profiles

Key-Value Operations:
  get <key>                  - Retrieve value for key
  put <key> <json>           - Store JSON value at key
  delete <key>               - Delete key

Cluster Management:
  members                    - List cluster members
  health                     - Check service health

User Management:
  user get <uuid>            - Get user details
  user create <nickname>     - Create new user (admin only)

System:
  help                       - Show this help
  exit, quit                 - Exit shell
  clear                      - Clear screen
`
	fmt.Println(help)
}

func main() {
	client := NewKVSClient("http://localhost:8090")

	// Setup readline
	rl, err := readline.NewEx(&readline.Config{
		Prompt:          cyan("kvs> "),
		HistoryFile:     os.Getenv("HOME") + "/.kvs_history",
		AutoComplete:    completer,
		InterruptPrompt: "^C",
		EOFPrompt:       "exit",
	})
	if err != nil {
		panic(err)
	}
	defer rl.Close()

	fmt.Println(magenta("KVS Interactive Shell"))
	fmt.Println("Type 'help' for available commands")
	fmt.Println()

	for {
		line, err := rl.Readline()
		if err != nil {
			break
		}

		line = strings.TrimSpace(line)
		if line == "" {
			continue
		}

		parts := parseCommand(line)
		if len(parts) == 0 {
			continue
		}

		cmd := parts[0]
		args := parts[1:]

		switch cmd {
		case "exit", "quit":
			fmt.Println("Goodbye!")
			return
		case "clear":
			print("\033[H\033[2J")
		case "help":
			client.handleHelp(args)
		case "connect":
			client.handleConnect(args)
		case "auth":
			client.handleAuth(args)
		case "profile":
			client.handleProfile(args)
		case "get":
			client.handleGet(args)
		case "put":
			client.handlePut(args)
		case "delete":
			client.handleDelete(args)
		case "members":
			client.handleMembers(args)
		case "health":
			client.handleHealth(args)
		case "user":
			if len(args) > 0 && args[0] == "get" {
				client.handleUserGet(args[1:])
			} else {
				client.handleUserList(args)
			}
		default:
			fmt.Println(red("Unknown command:"), cmd)
			fmt.Println("Type 'help' for available commands")
		}
	}
}

// Auto-completion
var completer = readline.NewPrefixCompleter(
	readline.PcItem("connect"),
	readline.PcItem("auth"),
	readline.PcItem("profile",
		readline.PcItem("add"),
		readline.PcItem("use"),
		readline.PcItem("remove"),
	),
	readline.PcItem("get"),
	readline.PcItem("put"),
	readline.PcItem("delete"),
	readline.PcItem("members"),
	readline.PcItem("health"),
	readline.PcItem("user",
		readline.PcItem("get"),
		readline.PcItem("create"),
	),
	readline.PcItem("help"),
	readline.PcItem("exit"),
	readline.PcItem("quit"),
	readline.PcItem("clear"),
)

// Parse command line respecting quotes
func parseCommand(line string) []string {
	var parts []string
	var current strings.Builder
	var quoteChar byte // Track which quote char started this argument (' or ")
	inQuotes := false

	for i := 0; i < len(line); i++ {
		ch := line[i]

		// Check if this is a quote character at the start of a new argument
		if (ch == '"' || ch == '\'') && current.Len() == 0 && !inQuotes {
			// Starting a quoted argument - remember the quote type
			quoteChar = ch
			inQuotes = true
			continue // Don't add the quote itself
		}

		// Check if this is the closing quote
		if inQuotes && ch == quoteChar {
			// End quoted argument
			inQuotes = false
			quoteChar = 0
			continue // Don't add the quote itself
		}

		// Handle spaces/tabs
		if (ch == ' ' || ch == '\t') && !inQuotes {
			if current.Len() > 0 {
				parts = append(parts, current.String())
				current.Reset()
			}
			continue
		}

		// Add all other characters (including quotes inside unquoted args)
		current.WriteByte(ch)
	}

	if current.Len() > 0 {
		parts = append(parts, current.String())
	}

	return parts
}