package configuration

import (
	"errors"
	"fmt"

	"github.com/knadh/koanf"
	"github.com/knadh/koanf/parsers/yaml"
	"github.com/knadh/koanf/providers/env"
	"github.com/knadh/koanf/providers/file"
	"github.com/knadh/koanf/providers/posflag"
	"github.com/spf13/pflag"

	"github.com/authelia/authelia/v4/internal/configuration/schema"
)

// NewYAMLFileSource returns a Source configured to load from a specified YAML path. If there is an issue accessing this
// path it also returns an error.
func NewYAMLFileSource(path string) (source *YAMLFileSource) {
	return &YAMLFileSource{
		koanf: koanf.New(constDelimiter),
		path:  path,
	}
}

// NewYAMLFileSources returns a slice of Source configured to load from specified YAML files.
func NewYAMLFileSources(paths []string) (sources []*YAMLFileSource) {
	for _, path := range paths {
		source := NewYAMLFileSource(path)

		sources = append(sources, source)
	}

	return sources
}

// Name of the Source.
func (s YAMLFileSource) Name() (name string) {
	return fmt.Sprintf("yaml file(%s)", s.path)
}

// Merge the YAMLFileSource koanf.Koanf into the provided one.
func (s *YAMLFileSource) Merge(ko *koanf.Koanf, _ *schema.StructValidator) (err error) {
	return ko.Merge(s.koanf)
}

// Load the Source into the YAMLFileSource koanf.Koanf.
func (s *YAMLFileSource) Load(_ *schema.StructValidator) (err error) {
	if s.path == "" {
		return errors.New("invalid yaml path source configuration")
	}

	return s.koanf.Load(file.Provider(s.path), yaml.Parser())
}

// NewEnvironmentSource returns a Source configured to load from environment variables.
func NewEnvironmentSource(prefix, delimiter string) (source *EnvironmentSource) {
	return &EnvironmentSource{
		koanf:     koanf.New(constDelimiter),
		prefix:    prefix,
		delimiter: delimiter,
	}
}

// Name of the Source.
func (s EnvironmentSource) Name() (name string) {
	return "environment"
}

// Merge the EnvironmentSource koanf.Koanf into the provided one.
func (s *EnvironmentSource) Merge(ko *koanf.Koanf, _ *schema.StructValidator) (err error) {
	return ko.Merge(s.koanf)
}

// Load the Source into the EnvironmentSource koanf.Koanf.
func (s *EnvironmentSource) Load(_ *schema.StructValidator) (err error) {
	keyMap, ignoredKeys := getEnvConfigMap(schema.Keys, s.prefix, s.delimiter)

	return s.koanf.Load(env.ProviderWithValue(s.prefix, constDelimiter, koanfEnvironmentCallback(keyMap, ignoredKeys, s.prefix, s.delimiter)), nil)
}

// NewSecretsSource returns a Source configured to load from secrets.
func NewSecretsSource(prefix, delimiter string) (source *SecretsSource) {
	return &SecretsSource{
		koanf:     koanf.New(constDelimiter),
		prefix:    prefix,
		delimiter: delimiter,
	}
}

// Name of the Source.
func (s SecretsSource) Name() (name string) {
	return "secrets"
}

// Merge the SecretsSource koanf.Koanf into the provided one.
func (s *SecretsSource) Merge(ko *koanf.Koanf, val *schema.StructValidator) (err error) {
	for _, key := range s.koanf.Keys() {
		value, ok := ko.Get(key).(string)

		if ok && value != "" {
			val.Push(fmt.Errorf(errFmtSecretAlreadyDefined, key))
		}
	}

	return ko.Merge(s.koanf)
}

// Load the Source into the SecretsSource koanf.Koanf.
func (s *SecretsSource) Load(val *schema.StructValidator) (err error) {
	keyMap := getSecretConfigMap(schema.Keys, s.prefix, s.delimiter)

	return s.koanf.Load(env.ProviderWithValue(s.prefix, constDelimiter, koanfEnvironmentSecretsCallback(keyMap, val)), nil)
}

// NewCommandLineSourceWithMapping creates a new command line configuration source with a map[string]string which converts
// flag names into other config key names. If includeValidKeys is true we also allow any flag with a name which matches
// the list of valid keys into the koanf.Koanf, otherwise everything not in the map is skipped. Unchanged flags are also
// skipped unless includeUnchangedKeys is set to true.
func NewCommandLineSourceWithMapping(flags *pflag.FlagSet, mapping map[string]string, includeValidKeys, includeUnchangedKeys bool) (source *CommandLineSource) {
	return &CommandLineSource{
		koanf:    koanf.New(constDelimiter),
		flags:    flags,
		callback: koanfCommandLineWithMappingCallback(mapping, includeValidKeys, includeUnchangedKeys),
	}
}

// Name of the Source.
func (s CommandLineSource) Name() (name string) {
	return "command-line"
}

// Merge the CommandLineSource koanf.Koanf into the provided one.
func (s *CommandLineSource) Merge(ko *koanf.Koanf, val *schema.StructValidator) (err error) {
	return ko.Merge(s.koanf)
}

// Load the Source into the YAMLFileSource koanf.Koanf.
func (s *CommandLineSource) Load(_ *schema.StructValidator) (err error) {
	if s.callback != nil {
		return s.koanf.Load(posflag.ProviderWithFlag(s.flags, ".", s.koanf, s.callback), nil)
	}

	return s.koanf.Load(posflag.Provider(s.flags, ".", s.koanf), nil)
}

// NewDefaultSources returns a slice of Source configured to load from specified YAML files.
func NewDefaultSources(filePaths []string, prefix, delimiter string) (sources []Source) {
	fileSources := NewYAMLFileSources(filePaths)
	for _, source := range fileSources {
		sources = append(sources, source)
	}

	sources = append(sources, NewEnvironmentSource(prefix, delimiter))
	sources = append(sources, NewSecretsSource(prefix, delimiter))

	return sources
}