package app

import (
	"bytes"
	"io"
	"os"
	"strings"

	"git.sendico.io/tech/sxchnge/notifications/bus"
	"git.sendico.io/tech/sxchnge/notifications/email"
	db "git.sendico.io/tech/sxchnge/shared/database"
	merrors "git.sendico.io/tech/sxchnge/shared/errors"
	"git.sendico.io/tech/sxchnge/shared/messaging"
	"gopkg.in/yaml.v3"
)

type Config struct {
	Queue     bus.Config        `yaml:"queue"`
	Messaging messaging.Config  `yaml:"messaging"`
	Listen    string            `yaml:"listen"`
	TLSCert   string            `yaml:"tls_cert"`
	TLSKey    string            `yaml:"tls_key"`
	Database  db.Config         `yaml:"database"`
	Templates string            `yaml:"templates"`
	Callers   map[string]string `yaml:"callers"` // caller -> token environment variable
	Email     email.Config      `yaml:"email"`
}

func Load(path string) (Config, error) {
	c := Config{Queue: bus.DefaultConfig()}
	data, err := os.ReadFile(path)
	if err != nil {
		return c, merrors.OpaqueWrap(merrors.ErrInvalidArg, err, "cannot read configuration")
	}
	decoder := yaml.NewDecoder(bytes.NewReader(data))
	decoder.KnownFields(true)
	if err = decoder.Decode(&c); err != nil {
		return c, merrors.InvalidArgument("invalid configuration")
	}
	if err = decoder.Decode(new(any)); err != io.EOF {
		return c, merrors.InvalidArgument("unexpected configuration content")
	}
	if c.Listen == "" || c.Database.Driver != db.Mongo || c.Messaging.Driver != messaging.BBNats || c.Templates == "" || len(c.Callers) == 0 {
		return c, merrors.InvalidArgument("missing notification configuration")
	}
	if (c.TLSCert == "") != (c.TLSKey == "") {
		return c, merrors.InvalidArgument("both TLS certificate and key must be configured together")
	}
	if err = c.Queue.Validate(); err != nil {
		return c, err
	}
	seen := map[string]bool{}
	for caller, env := range c.Callers {
		token := os.Getenv(env)
		if strings.TrimSpace(caller) == "" || len(strings.TrimSpace(token)) < 32 || seen[token] {
			return c, merrors.InvalidArgument("caller credentials must be unique and at least 32 bytes")
		}
		seen[token] = true
	}
	return c, nil
}