/*
Copyright 2022 CAcert Inc.
SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

//go:generate go run github.com/shamaton/msgpackgen

// Package messages contains structure definitions for protocol messages
package messages

import (
	"crypto/x509"
	"encoding/json"
	"encoding/pem"
	"fmt"
	"math/big"
	"strings"
	"time"

	// required for msgpackgen
	_ "github.com/dave/jennifer"

	"github.com/google/uuid"
)

type CommandCode int8

const (
	CmdUndef CommandCode = iota
	CmdHealth
	CmdFetchCRL
)

var commandNames = map[CommandCode]string{
	CmdUndef:    "UNDEFINED",
	CmdHealth:   "HEALTH",
	CmdFetchCRL: "FETCH CRL",
}

func (c CommandCode) String() string {
	if name, ok := commandNames[c]; ok {
		return name
	}

	return fmt.Sprintf("unknown %d", c)
}

type ResponseCode int8

const (
	RespError ResponseCode = -1
	RespUndef ResponseCode = iota
	RespHealth
	RespFetchCRL
)

var responseNames = map[ResponseCode]string{
	RespError:    "ERROR",
	RespUndef:    "UNDEFINED",
	RespHealth:   "HEALTH",
	RespFetchCRL: "FETCH CRL",
}

func (c ResponseCode) String() string {
	if name, ok := responseNames[c]; ok {
		return name
	}

	return fmt.Sprintf("unknown %d", c)
}

type CommandAnnounce struct {
	Code    CommandCode `msgpack:"code"`
	ID      string      `msgpack:"id"`
	Created time.Time   `msgpack:"created"`
}

func (r *CommandAnnounce) String() string {
	return fmt.Sprintf("code=%s, id=%s, created=%s", r.Code, r.ID, r.Created.Format(time.RFC3339))
}

type ResponseAnnounce struct {
	Code    ResponseCode `msgpack:"code"`
	Created time.Time    `msgpack:"created"`
	ID      string       `msgpack:"id"`
}

func (r *ResponseAnnounce) String() string {
	return fmt.Sprintf("code=%s, id=%s, created=%s", r.Code, r.ID, r.Created.Format(time.RFC3339))
}

type FetchCRLCommand struct {
	IssuerID    string `msgpack:"issuer_id"`
	LastKnownID []byte `msgpack:"last_known_id"`
}

func (f *FetchCRLCommand) String() string {
	builder := &strings.Builder{}

	_, _ = fmt.Fprintf(builder, "issuerId='%s'", f.IssuerID)

	if f.LastKnownID != nil {
		_, _ = fmt.Fprintf(builder, ", lastKnownId=0x%s", new(big.Int).SetBytes(f.LastKnownID).Text(16))
	}

	return builder.String()
}

type HealthCommand struct {
}

func (h *HealthCommand) String() string {
	return ""
}

type HealthInfo struct {
	Source   string
	Healthy  bool
	MoreInfo map[string]string
}

func (i *HealthInfo) String() string {
	builder := &strings.Builder{}

	_, _ = fmt.Fprintf(builder, "source: %s, healthy: %v, [\n", i.Source, i.Healthy)

	for k, v := range i.MoreInfo {
		_, _ = fmt.Fprintf(builder, "  %s: '%s'\n", k, v)
	}

	_, _ = builder.WriteRune(']')

	return builder.String()
}

type ProfileUsage string

const (
	UsageOcsp   ProfileUsage = "ocsp"
	UsagePerson ProfileUsage = "person"
	UsageClient ProfileUsage = "client"
	UsageCode   ProfileUsage = "code"
	UsageServer ProfileUsage = "server"
)

var validProfileUsages = map[string]ProfileUsage{
	"ocsp":   UsageOcsp,
	"person": UsagePerson,
	"client": UsageClient,
	"code":   UsageCode,
	"server": UsageServer,
}

func ParseUsage(u string) (ProfileUsage, error) {
	usage, ok := validProfileUsages[u]
	if !ok {
		return "", fmt.Errorf("unsupported profile usage: %s", u)
	}

	return usage, nil
}

type CAProfile struct {
	Name   string       `json:"name"`
	UseFor ProfileUsage `json:"use-for"`
}

func (p CAProfile) String() string {
	return fmt.Sprintf("profile['%s': '%s']", p.Name, p.UseFor)
}

type CertificateInfo struct {
	Status     string      `json:"status"`
	Signing    bool        `json:"signing"`
	Profiles   []CAProfile `json:"profiles"`
	ValidUntil time.Time   `json:"valid-until"`
}

func (i CertificateInfo) String() string {
	marshal, _ := json.Marshal(i)

	return string(marshal)
}

func (i *HealthInfo) ParseCertificateInfo(info string) (*CertificateInfo, error) {
	certInfo := CertificateInfo{}

	err := json.Unmarshal([]byte(info), &certInfo)
	if err != nil {
		return nil, fmt.Errorf("could not parse certificate information: %w", err)
	}

	return &certInfo, nil
}

type HealthResponse struct {
	Version string `msgpack:"version"`
	Healthy bool   `msgpack:"healthy"`
	Info    []*HealthInfo
}

func (h *HealthResponse) String() string {
	builder := &strings.Builder{}

	_, _ = fmt.Fprintf(builder, "signer version=%s, healthy=%v, health data:\n", h.Version, h.Healthy)

	for _, info := range h.Info {
		_, _ = fmt.Fprintf(builder, " - %s", info)
	}

	return builder.String()
}

type FetchCRLResponse struct {
	IssuerID  string `msgpack:"issuer_id"`
	IsDelta   bool   `msgpack:"is_delta"`
	UnChanged bool   `msgpack:"unchanged"`
	CRLData   []byte `msgpack:"crl_data"`
	CRLNumber []byte `msgpack:"crl_number"`
}

func (r *FetchCRLResponse) String() string {
	builder := &strings.Builder{}

	_, _ = fmt.Fprintf(
		builder,
		"issuer id=%s, delta CRL data=%t, unchanged=%t, CRL number=0x%s",
		r.IssuerID,
		r.IsDelta,
		r.UnChanged,
		new(big.Int).SetBytes(r.CRLNumber).Text(16),
	)

	if r.UnChanged {
		return builder.String()
	}

	if r.IsDelta {
		_, _ = fmt.Fprint(builder, ", delta CRL data not shown")

		return builder.String()
	}

	revocationList, err := x509.ParseRevocationList(r.CRLData)
	if err != nil {
		_, _ = fmt.Fprintf(builder, ", could not parse CRL: %s", err.Error())

		return builder.String()
	}

	_, _ = fmt.Fprintf(
		builder,
		", CRL info: issuer=%s, number=0x%s, next update=%s, revoked certificates=%d",
		revocationList.Issuer,
		revocationList.Number.Text(16),
		revocationList.NextUpdate,
		len(revocationList.RevokedCertificates),
	)
	_, _ = builder.WriteString(", CRL data:\n")
	_ = pem.Encode(builder, &pem.Block{
		Type:  "CERTIFICATE REVOCATION LIST",
		Bytes: r.CRLData,
	})

	return builder.String()
}

type ErrorResponse struct {
	Message string `msgpack:"message"`
}

func (e *ErrorResponse) String() string {
	return fmt.Sprintf("message=%s", e.Message)
}

func BuildCommandAnnounce(code CommandCode) (*CommandAnnounce, error) {
	commandID, err := uuid.NewUUID()
	if err != nil {
		return nil, fmt.Errorf("could not build command id: %w", err)
	}

	return &CommandAnnounce{Code: code, ID: commandID.String(), Created: time.Now().UTC()}, nil
}

func BuildResponseAnnounce(code ResponseCode, commandID string) *ResponseAnnounce {
	return &ResponseAnnounce{Code: code, ID: commandID, Created: time.Now().UTC()}
}