package config

import (
	"errors"
	"fmt"
	"os"
	"strings"

	"go.uber.org/multierr"
	"gopkg.in/yaml.v3"
)

var ErrLoggingDisabled error = errors.New("logging is disabled")

type Config struct {
	Environment   Environment         `yaml:"environment"`
	Server        ServerConfig        `yaml:"server"`
	Database      DatabaseConfig      `yaml:"database"`
	RateLimit     RateLimitConfig     `yaml:"rate_limit"`
	Observability ObservabilityConfig `yaml:"observability"`
}

func (c *Config) Validate() error {
	var err error

	err = addValidationError(err, "environment validation error", c.Environment.PreprocessAndValidate())
	err = addValidationError(err, "server section validation error", c.Server.Validate())
	err = addValidationError(err, "database section validation error", c.Database.Validate())
	err = addValidationError(err, "rate_limit section validation error", c.RateLimit.Validate())
	err = addValidationError(err, "observability section validation error", c.Observability.Validate())

	return err
}

func ReadConfig(path string) (Config, error) {
	var c Config
	yamlFile, err := os.ReadFile(path)
	if err != nil {
		return c, fmt.Errorf("could not read config: %w", err)
	}
	err = yaml.Unmarshal(yamlFile, &c)
	if err != nil {
		return c, fmt.Errorf("could not parse yaml: %w", err)
	}
	return c, nil
}

type Environment string

var (
	ProductionEnvironment  Environment = "production"
	DevelopmentEnvironment Environment = "development"
)

func (e *Environment) PreprocessAndValidate() error {
	preprocessed := strings.ToLower(string(*e))
	switch preprocessed {
	case string(ProductionEnvironment), "prod":
		*e = ProductionEnvironment
		return nil
	case string(DevelopmentEnvironment), "dev":
		*e = DevelopmentEnvironment
		return nil
	default:
		return fmt.Errorf("invalid Environment value: '%v'", *e)
	}
}

func addValidationError(err error, text string, validationError error) error {
	if validationError == nil {
		return err
	}
	return multierr.Append(err, fmt.Errorf("%s: %w", text, validationError))
}