package config

import (
	"bytes"
	"encoding/json"
	"log"
	"os"
	"path/filepath"
	"slices"

	"gitlab.hamburg.ccc.de/ccchh/spaceapid/types"
)

const (
	envConfigPath = "CONFIG_PATH"
)

// getConfigPath gets the spaceapid configuration from the respective environment variables
func getConfigPath() string {
	// JSON template path
	configPath, ok := os.LookupEnv(envConfigPath)
	if !ok || configPath == "" {
		log.Fatalln("Could not retrieve", envConfigPath, "env variable or variable is empty")
	}
	// Save as absolute path
	absConfigPath, err := filepath.Abs(configPath)
	if err != nil {
		log.Fatalln("Failed converting", configPath, "to absolute path:", err)
	}
	return absConfigPath
}

// ParseConfiguration returns the config from file
func ParseConfiguration() (conf SpaceapidConfig) {
	log.Println("Parsing configuration file")
	// Read file
	file, err := os.ReadFile(getConfigPath())
	if err != nil {
		log.Fatalln("Failed reading file:", err)
	}

	// Parse JSON
	dec := json.NewDecoder(bytes.NewReader(file))
	dec.DisallowUnknownFields()
	err = dec.Decode(&conf)
	if err != nil {
		log.Fatalln("Could not parse spaceapid config file:", err)
	}

	// Check if compatible with v14
	if !slices.Contains(conf.Response.APICompatibility, "14") {
		log.Fatalln("Provided file doesn't specify compatibility with API version 14")
	}

	// Initialise fields for environment sensors
	conf.Response.Sensors = make(map[string][]types.EnvironmentSensor)
	for key, sensorConfigs := range conf.Dynamic.Sensors {
		conf.Response.Sensors[key] = make([]types.EnvironmentSensor, len(sensorConfigs))
		for i, sensorConfig := range sensorConfigs {
			conf.Response.Sensors[key][i] = sensorConfig.SensorData
		}
	}

	return
}