package config

//go:generate go run ../../cmd/cspgenerator/

import (
	"fmt"
	"os"
	"reflect"

	"github.com/crewjam/csp"
	"github.com/fatih/structtag"
	"gitlab.com/tozd/go/errors"
)

func GenerateCSP() errors.E {
	headerType := reflect.TypeFor[csp.Header]()
	file, err := os.OpenFile("./csp.go", os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0)
	if err != nil {
		return errors.WithMessage(err, "could not open file")
	}
	defer func() {
		err := file.Close()
		if err != nil {
			panic("could not close file: " + err.Error())
		}
	}()

	_, err = fmt.Fprintf(file, `package config

// Code generated  DO NOT EDIT.

import (
	"github.com/crewjam/csp"
)

type CSP struct {
`)
	if err != nil {
		return errors.WithMessage(err, "could not write to output")
	}

	for _, field := range reflect.VisibleFields(headerType) {
		fieldType := field.Type
		tags, err := structtag.Parse(string(field.Tag))
		if err != nil {
			return errors.WithMessage(err, "could not write to output")
		}
		cspTag, err := tags.Get("csp")
		if err != nil {
			return errors.WithMessage(err, "could not get csp tag")
		}
		err = tags.Set(&structtag.Tag{
			Key:  "toml",
			Name: cspTag.Name,
		})
		if err != nil {
			return errors.WithMessage(err, "could not set toml tag")
		}

		_, err = fmt.Fprintf(file, "\t%-23s %-28s `%s`\n", field.Name, fieldType, tags.String())
		if err != nil {
			return errors.WithMessage(err, "could not write to output")
		}
	}
	_, err = fmt.Fprintln(file, "}")
	if err != nil {
		return errors.WithMessage(err, "could not write to output")
	}

	_, err = fmt.Fprintln(file, `
func (c *CSP) String() string {
	return csp.Header(*c).String()
}`)
	if err != nil {
		return errors.WithMessage(err, "could not write to output")
	}

	return nil
}