// Copyright 2022 Woodpecker Authors
// Copyright 2019 Laszlo Fogas
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"bytes"
	"encoding/json"
	"os"
	"strings"

	"github.com/rs/zerolog/log"
)

type AgentConfig struct {
	AgentID int64 `json:"agent_id"`
}

const defaultAgentIDValue = int64(-1)

func readAgentConfig(agentConfigPath string) AgentConfig {
	conf := AgentConfig{
		AgentID: defaultAgentIDValue,
	}

	if agentConfigPath == "" {
		return conf
	}

	rawAgentConf, err := os.ReadFile(agentConfigPath)
	if err != nil {
		if os.IsNotExist(err) {
			log.Info().Msgf("no agent config found at '%s', start with defaults", agentConfigPath)
		} else {
			log.Error().Err(err).Msgf("could not open agent config at '%s'", agentConfigPath)
		}
		return conf
	}
	if strings.TrimSpace(string(rawAgentConf)) == "" {
		return conf
	}

	if err := json.Unmarshal(rawAgentConf, &conf); err != nil {
		log.Error().Err(err).Msg("could not parse agent config")
	}
	return conf
}

func writeAgentConfig(conf AgentConfig, agentConfigPath string) error {
	rawAgentConf, err := json.Marshal(conf)
	if err != nil {
		log.Error().Err(err).Msg("could not marshal agent config")
		return err
	}

	// get old config
	oldRawAgentConf, _ := os.ReadFile(agentConfigPath)

	// if config differ write to disk
	if !bytes.Equal(rawAgentConf, oldRawAgentConf) {
		if err := os.WriteFile(agentConfigPath, rawAgentConf, 0o644); err != nil {
			log.Error().Err(err).Msgf("could not persist agent config at '%s'", agentConfigPath)
			return err
		}
	}

	return nil
}