package config

import (
    "encoding/json"
    "os"
    "path/filepath"
    "strings"
)

type Config struct {
    Listen             string            `json:"listen"`
    DiscoveryPort      int               `json:"discovery_port"`
    DiscoveryTimeoutMs int               `json:"discovery_timeout_ms"`
    OfflineAfterMs     int               `json:"offline_after_ms"`
    AgentToken         string            `json:"agent_token"`
    Concurrency        int               `json:"concurrency"`
    DataDir            string            `json:"data_dir,omitempty"`
    DBPath             string            `json:"db_path,omitempty"`
    LogDir             string            `json:"log_dir,omitempty"`
    MediaRepoPath      string            `json:"media_repo_path,omitempty"` // explicit import-only source; not used for runtime rendering
    AlarmRetentionDays int               `json:"alarm_retention_days"`     // auto-delete alarms older than N days, 0=keep forever
    DeviceAliases      map[string]string `json:"device_aliases,omitempty"`
    path               string
}

func LoadConfig(path string) (*Config, error) {
    file, err := os.Open(path)
    if err != nil {
        return nil, err
    }
    defer file.Close()

    var cfg Config
    decoder := json.NewDecoder(file)
    if err := decoder.Decode(&cfg); err != nil {
        return nil, err
    }
    cfg.path = path

    return &cfg, nil
}

func (c *Config) Save() error {
    if c == nil || c.path == "" {
        return nil
    }
    body, err := json.MarshalIndent(c, "", "  ")
    if err != nil {
        return err
    }
    return os.WriteFile(c.path, append(body, '\n'), 0o644)
}

func (c *Config) DataDirOrDefault() string {
    if c != nil && strings.TrimSpace(c.DataDir) != "" {
        return filepath.Clean(strings.TrimSpace(c.DataDir))
    }
    return "data"
}

func (c *Config) DBPathOrDefault() string {
    if c != nil && strings.TrimSpace(c.DBPath) != "" {
        return filepath.Clean(strings.TrimSpace(c.DBPath))
    }
    return filepath.Join(c.DataDirOrDefault(), "app.db")
}

func (c *Config) LogDirOrDefault() string {
    if c != nil && strings.TrimSpace(c.LogDir) != "" {
        return filepath.Clean(strings.TrimSpace(c.LogDir))
    }
    return filepath.Join(c.DataDirOrDefault(), "logs")
}