package conf

import (
	`encoding/json`
	`encoding/xml`
	`hash`
	`os`

	`github.com/BurntSushi/toml`
	`github.com/creasty/defaults`
	`github.com/davecgh/go-spew/spew`
	`github.com/goccy/go-yaml`
	`github.com/zeebo/blake3`
	`r00t2.io/gobroke/tplCmd`
	`r00t2.io/goutils/logging`
	`r00t2.io/sysutils/paths`
)

/*
	Checksum guarantees a standard checksum of a configuration.
	If you are comparing new vs. old configs, be sure to use this function
	and compare against a Config.Checksum() to ensure consistent hashing algorithms etc.
*/
func Checksum(confBytes []byte) (cksum []byte, err error) {

	// If built with CGO enabled, this'll take advantage of SIMD.
	// Should be fast enough without it, though.
	var h hash.Hash = blake3.New()

	if _, err = h.Write(confBytes); err != nil {
		return
	}

	cksum = h.Sum(nil)

	return
}

/*
	ChecksumPath is a convenience wrapper around Checksum, operating on a filepath instead of bytes.
*/
func ChecksumPath(confPath string) (cksum []byte, err error) {

	var b []byte

	if err = paths.RealPath(&confPath); err != nil {
		return
	}

	if b, err = os.ReadFile(confPath); err != nil {
		return
	}

	if cksum, err = Checksum(b); err != nil {
		return
	}

	return
}

// NewConfig returns a conf.Config from filepath path.
func NewConfig(path string, debug bool, log logging.Logger) (cfg *Config, err error) {

	var b []byte

	if log == nil {
		log = &logging.NullLogger{}
	}

	log.Debug("conf.NewConfig: New config from path '%s'", path)

	if err = paths.RealPath(&path); err != nil {
		log.Err("conf.NewConfig: Received error canonizing config path '%s': %s", path, err)
		return
	}
	log.Debug("conf.NewConfig: Canonized configuration path to '%s'", path)

	if cfg, err = NewConfigFromBytes(b, debug, log); err != nil {
		log.Err("conf.NewConfig: Received error parsing config '%s': %s", path, err)
		return
	}
	cfg.confPath = new(string)
	*cfg.confPath = path

	log.Debug("conf.NewConfig: Successfully parsed and loaded configuration '%s'", path)

	return
}

// NewConfigFromBytes returns a conf.Config from bytes b. b may be a JSON, TOML, XML, or YAML representation.
func NewConfigFromBytes(b []byte, debug bool, log logging.Logger) (cfg *Config, err error) {

	var tplBytes []byte

	if b == nil || len(b) == 0 {
		return
	}

	if log == nil {
		log = &logging.NullLogger{}
	}

	log.Debug("conf.NewConfigFromBytes: New config from %d bytes.", len(b))
	log.Debug("conf.NewConfigFromBytes: Config before parsing:\n%s", string(b))

	if err = json.Unmarshal(b, &cfg); err != nil {
		if err = xml.Unmarshal(b, &cfg); err != nil {
			if err = yaml.Unmarshal(b, &cfg); err != nil {
				if err = toml.Unmarshal(b, &cfg); err != nil {
					log.Err("conf.NewConfigFromBytes: Unable to parse config as JSON, XML, YAML, or TOML; config invalid.")
					err = ErrUnkownSyntax
					return
				} else {
					log.Debug("conf.NewConfigFromBytes: Config parsed as TOML.")
				}
			} else {
				log.Debug("conf.NewConfigFromBytes: Config parsed as YAML.")
			}
		} else {
			log.Debug("conf.NewConfigFromBytes: Config parsed as XML.")
		}
	} else {
		log.Debug("conf.NewConfigFromBytes: Config parsed as JSON.")
	}

	if err = defaults.Set(cfg); err != nil {
		return
	}
	log.Debug("conf.NewConfigFromBytes: Configuration after parsing and defaults:\n%s", spew.Sdump(cfg))

	if err = validate.Struct(cfg); err != nil {
		log.Err("conf.NewConfigFromBytes: Config validation failed: %v", err)
		return
	}

	cfg.log = log
	cfg.debug = debug

	for _, t := range cfg.Tunnels {
		if t == nil {
			continue
		}
		t.cfg = cfg
		if t.Username == nil {
			if cfg.Username == nil {
				log.Err(
					"conf.NewConfigFromBytes: Username is not provided for tunnel %d and no default username was provided.",
					t.TunnelID,
				)
				err = ErrMissingUser
				return
			} else {
				t.Username = cfg.Username
			}
		}
		if t.TemplateConfigs != nil && len(t.TemplateConfigs) > 0 {
			for _, tpl := range t.TemplateConfigs {
				if tpl == nil {
					continue
				}
				if err = paths.RealPath(&tpl.Template); err != nil {
					log.Err("conf.NewConfigFromBytes: Unable to canonize path to template '%s': %s", tpl.Template, err)
					return
				}
				if err = paths.RealPath(&tpl.Dest); err != nil {
					log.Err("conf.NewConfigFromBytes: Unable to canonize path to destination '%s': %s", tpl.Dest, err)
					return
				}
				if tplBytes, err = os.ReadFile(tpl.Template); err != nil {
					log.Err("conf.NewConfigFromBytes: Unable to read template file '%s': %s", tpl.Template, err)
					return
				}
				tpl.Tpl = tplCmd.GetTpl()
				if _, err = tpl.Tpl.Parse(string(tplBytes)); err != nil {
					log.Err("conf.NewConfigFromBytes: Unable to parse template file '%s': %s", tpl.Template, err)
					return
				}
				if tpl.Perms != nil {
					if err = tpl.Perms.SetMissing(); err != nil {
						log.Err("conf.NewConfigFromBytes: Unable to enrich permissions for template '%s': %s", tpl.Template, err)
						return
					}
				}
			}
		}
	}

	if cfg.cksum, err = Checksum(b); err != nil {
		log.Err("conf.NewConfigFromBytes: Error calculating checksum: %s", err)
		return
	}

	log.Debug("conf.NewConfigFromBytes: Successfully parsed and loaded configuration.")

	return
}