package main

import (
	"crypto/rand"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"
)

type NtfyConfig struct {
	Server           string   `json:"server"`
	Topic            string   `json:"topic"`             // server events (questions etc.)
	AllowedTopics    []string `json:"allowed_topics"`    // POST /api/notify may only use these
	Enabled          bool     `json:"enabled"`
	NotifyOnQuestion bool     `json:"notify_on_question"`
}

type Config struct {
	Listen    string     `json:"listen"`
	Token     string     `json:"token"`
	AgentCmd  string     `json:"agent_cmd"`
	AgentArgs []string   `json:"agent_args"`
	Workdir   string     `json:"workdir"`
	ShareDir  string     `json:"share_dir"`
	ShareExts []string   `json:"share_exts"`
	PollMs    int        `json:"poll_ms"`
	Cols      int        `json:"cols"`
	Rows      int        `json:"rows"`
	Ntfy      NtfyConfig `json:"ntfy"`

	path string
}

func defaultConfig() *Config {
	home, _ := os.UserHomeDir()
	return &Config{
		Listen:    "127.0.0.1:8788",
		AgentCmd:  "agy",
		AgentArgs: []string{},
		Workdir:   home,
		ShareDir:  filepath.Join(home, ".local/share/helmd/shares"),
		ShareExts: []string{".html", ".htm", ".md", ".txt", ".json", ".png", ".jpg", ".jpeg", ".gif", ".svg", ".pdf"},
		PollMs:    500,
		Cols:      200,
		Rows:      50,
		Ntfy: NtfyConfig{
			Server:           "https://ntfy.brasse-pc.eu",
			Topic:            "agent-helm",
			AllowedTopics:    []string{"agent-helm", "claude"},
			Enabled:          true,
			NotifyOnQuestion: true,
		},
	}
}

func configPath() string {
	if p := os.Getenv("HELMD_CONFIG"); p != "" {
		return p
	}
	dir, err := os.UserConfigDir()
	if err != nil {
		dir = "."
	}
	return filepath.Join(dir, "helmd", "config.json")
}

// loadConfig reads the config file, creating it with defaults (and a
// fresh token) on first run.
func loadConfig(path string) (*Config, error) {
	cfg := defaultConfig()
	cfg.path = path
	data, err := os.ReadFile(path)
	if os.IsNotExist(err) {
		cfg.Token = newToken()
		if err := cfg.Save(); err != nil {
			return nil, err
		}
		fmt.Fprintf(os.Stderr, "helmd: skapade %s (ny token genererad)\n", path)
		return cfg, nil
	}
	if err != nil {
		return nil, err
	}
	if err := json.Unmarshal(data, cfg); err != nil {
		return nil, fmt.Errorf("%s: %w", path, err)
	}
	if cfg.Token == "" {
		cfg.Token = newToken()
		if err := cfg.Save(); err != nil {
			return nil, err
		}
	}
	return cfg, nil
}

func (c *Config) Save() error {
	if err := os.MkdirAll(filepath.Dir(c.path), 0o755); err != nil {
		return err
	}
	data, err := json.MarshalIndent(c, "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(c.path, append(data, '\n'), 0o600)
}

func newToken() string {
	b := make([]byte, 24)
	if _, err := rand.Read(b); err != nil {
		panic(err)
	}
	return hex.EncodeToString(b)
}

func (c *Config) extAllowed(name string) bool {
	ext := strings.ToLower(filepath.Ext(name))
	for _, e := range c.ShareExts {
		if ext == e {
			return true
		}
	}
	return false
}

func (c *Config) topicAllowed(topic string) bool {
	for _, t := range c.Ntfy.AllowedTopics {
		if topic == t {
			return true
		}
	}
	return false
}