package config

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"os"
	"slices"
	"strings"

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

const (
	envConfigPath = "CONFIG_PATH"
)

type pathsT []string

func (p *pathsT) String() string {
	return fmt.Sprint(*p)
}

func (p *pathsT) Set(s string) error {
	*p = make(pathsT, 0)
	for _, path := range strings.Split(s, ",") {
		*p = append(*p, path)
	}
	return nil
}

var (
	flagConfigPaths pathsT
)

func init() {
	flag.Var(&flagConfigPaths, "c", "Comma-separated list of config file paths. Parsed in order of appearance. Values get overwritten by files parsed later.")
}

func getConfigPaths() (paths pathsT) {
	// Get paths from env variable and if env var present override cli flags
	configPath, ok := os.LookupEnv(envConfigPath)
	if ok {
		if configPath == "" {
			log.Fatalln("Env variable", envConfigPath, "is present but empty.")
		}
		_ = flagConfigPaths.Set(configPath)
	}

	for _, path := range flagConfigPaths {
		_, err := os.Stat(path)
		if err != nil {
			log.Fatalln("Config file", path, "doesn't exist or is not accessible, error:", err)
		}
		paths = append(paths, path)
	}

	// If paths is still empty we are missing something
	if len(paths) == 0 {
		log.Fatalln("Neither the env variable nor cli flag was specified, we are missing a config file.")
	}
	return
}

// ParseConfiguration returns the config from file
func ParseConfiguration() (conf SpaceapidConfig) {
	log.Println("Parsing configuration files")

	paths := getConfigPaths()
	log.Println(paths)
	for _, path := range paths {
		// Read file
		file, err := os.ReadFile(path)
		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
}