package template

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

	"github.com/BurntSushi/toml"
	"github.com/pkg/errors"
	"go.yaml.in/yaml/v3"
)

func file(ctx context.Context, templateVars any, errorOnMissing bool) func(v string) (string, error) {
	return func(v string) (string, error) {
		if v == "" {
			return "", nil
		}

		fileBytes, err := os.ReadFile(os.ExpandEnv(v))
		if err != nil {
			return "", errors.Wrap(err, "failed to read file")
		}

		renderedBytes, err := ExecuteFileTemplate(ctx, string(fileBytes), templateVars, errorOnMissing)
		if err != nil {
			return "", errors.Wrap(err, "failed to render file")
		}

		return string(bytes.TrimSpace(renderedBytes)), nil
	}
}

// toYAML takes an interface, marshals it to yaml, and returns a string. It will
// always return a string, even on marshal error (empty string).
//
// This is designed to be called from a template.
func toYAML(v any) string {
	data, err := yaml.Marshal(v)
	if err != nil {
		return err.Error()
	}

	return strings.TrimSuffix(string(data), "\n")
}

func toYAMLPretty(v any) string {
	var data bytes.Buffer

	encoder := yaml.NewEncoder(&data)
	encoder.SetIndent(2)

	err := encoder.Encode(v)
	if err != nil {
		return err.Error()
	}

	return strings.TrimSuffix(data.String(), "\n")
}

// fromYAML converts a YAML document into a map[string]any.
//
// This is not a general-purpose YAML parser, and will not parse all valid
// YAML documents. Additionally, because its intended use is within templates
// it tolerates errors. It will insert the returned error message string into
// m["Error"] in the returned map.
func fromYAML(str string) map[string]any {
	m := map[string]any{}

	if err := yaml.Unmarshal([]byte(str), &m); err != nil {
		m["Error"] = err.Error()
	}

	return m
}

// fromYAMLArray converts a YAML array into a []any.
//
// This is not a general-purpose YAML parser, and will not parse all valid
// YAML documents. Additionally, because its intended use is within templates
// it tolerates errors. It will insert the returned error message string as
// the first and only item in the returned array.
func fromYAMLArray(str string) []any {
	var a []any
	if err := yaml.Unmarshal([]byte(str), &a); err != nil {
		a = []any{err.Error()}
	}

	return a
}

// toTOML takes an interface, marshals it to toml, and returns a string. It will
// always return a string, even on marshal error (empty string).
//
// This is designed to be called from a template.
func toTOML(v any) string {
	b := bytes.NewBuffer(nil)
	e := toml.NewEncoder(b)

	err := e.Encode(v)
	if err != nil {
		return err.Error()
	}

	return b.String()
}

// fromTOML converts a TOML document into a map[string]any.
//
// This is not a general-purpose TOML parser, and will not parse all valid
// TOML documents. Additionally, because its intended use is within templates
// it tolerates errors. It will insert the returned error message string into
// m["Error"] in the returned map.
func fromTOML(str string) map[string]any {
	m := make(map[string]any)

	if err := toml.Unmarshal([]byte(str), &m); err != nil {
		m["Error"] = err.Error()
	}

	return m
}

// toJSON takes an interface, marshals it to json, and returns a string. It will
// always return a string, even on marshal error (empty string).
//
// This is designed to be called from a template.
func toJSON(v any) string {
	data, err := json.Marshal(v)
	if err != nil {
		return err.Error()
	}

	return string(data)
}

// fromJSON converts a JSON document into a map[string]any.
//
// This is not a general-purpose JSON parser, and will not parse all valid
// JSON documents. Additionally, because its intended use is within templates
// it tolerates errors. It will insert the returned error message string into
// m["Error"] in the returned map.
func fromJSON(str string) map[string]any {
	m := make(map[string]any)

	if err := json.Unmarshal([]byte(str), &m); err != nil {
		m["Error"] = err.Error()
	}

	return m
}

// fromJSONArray converts a JSON array into a []any.
//
// This is not a general-purpose JSON parser, and will not parse all valid
// JSON documents. Additionally, because its intended use is within templates
// it tolerates errors. It will insert the returned error message string as
// the first and only item in the returned array.
func fromJSONArray(str string) []any {
	var a []any
	if err := json.Unmarshal([]byte(str), &a); err != nil {
		a = []any{err.Error()}
	}

	return a
}