// Copyright 2023 Versity Software
// This file is 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.

package utils

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"net/http"
	"regexp"
	"strconv"
	"strings"
	"time"

	"github.com/gofiber/fiber/v2"
	"github.com/valyala/fasthttp"
	"github.com/versity/versitygw/s3err"
)

var (
	bucketNameRegexp   = regexp.MustCompile(`^[a-z0-9][a-z0-9.-]+[a-z0-9]$`)
	bucketNameIpRegexp = regexp.MustCompile(`^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$`)
)

func GetUserMetaData(headers *fasthttp.RequestHeader) (metadata map[string]string) {
	metadata = make(map[string]string)
	headers.DisableNormalizing()
	headers.VisitAllInOrder(func(key, value []byte) {
		hKey := string(key)
		if strings.HasPrefix(strings.ToLower(hKey), "x-amz-meta-") {
			trimmedKey := hKey[11:]
			headerValue := string(value)
			metadata[trimmedKey] = headerValue
		}
	})
	headers.EnableNormalizing()

	return
}

func createHttpRequestFromCtx(ctx *fiber.Ctx, signedHdrs []string, contentLength int64) (*http.Request, error) {
	req := ctx.Request()
	var body io.Reader
	if IsBigDataAction(ctx) {
		body = req.BodyStream()
	} else {
		body = bytes.NewReader(req.Body())
	}

	httpReq, err := http.NewRequest(string(req.Header.Method()), string(ctx.Context().RequestURI()), body)
	if err != nil {
		return nil, errors.New("error in creating an http request")
	}

	// Set the request headers
	req.Header.VisitAll(func(key, value []byte) {
		keyStr := string(key)
		if includeHeader(keyStr, signedHdrs) {
			httpReq.Header.Add(keyStr, string(value))
		}
	})

	// Check if Content-Length in signed headers
	// If content length is non 0, then the header will be included
	if !includeHeader("Content-Length", signedHdrs) {
		httpReq.ContentLength = 0
	} else {
		httpReq.ContentLength = contentLength
	}

	// Set the Host header
	httpReq.Host = string(req.Header.Host())

	return httpReq, nil
}

var (
	signedQueryArgs = map[string]bool{
		"X-Amz-Algorithm":     true,
		"X-Amz-Credential":    true,
		"X-Amz-Date":          true,
		"X-Amz-SignedHeaders": true,
		"X-Amz-Signature":     true,
	}
)

func createPresignedHttpRequestFromCtx(ctx *fiber.Ctx, signedHdrs []string, contentLength int64) (*http.Request, error) {
	req := ctx.Request()
	var body io.Reader
	if IsBigDataAction(ctx) {
		body = req.BodyStream()
	} else {
		body = bytes.NewReader(req.Body())
	}

	uri := string(ctx.Request().URI().Path())
	isFirst := true

	ctx.Request().URI().QueryArgs().VisitAll(func(key, value []byte) {
		_, ok := signedQueryArgs[string(key)]
		if !ok {
			if isFirst {
				uri += fmt.Sprintf("?%s=%s", key, value)
				isFirst = false
			} else {
				uri += fmt.Sprintf("&%s=%s", key, value)
			}
		}
	})

	httpReq, err := http.NewRequest(string(req.Header.Method()), uri, body)
	if err != nil {
		return nil, errors.New("error in creating an http request")
	}
	// Set the request headers
	req.Header.VisitAll(func(key, value []byte) {
		keyStr := string(key)
		if includeHeader(keyStr, signedHdrs) {
			httpReq.Header.Add(keyStr, string(value))
		}
	})

	// Check if Content-Length in signed headers
	// If content length is non 0, then the header will be included
	if !includeHeader("Content-Length", signedHdrs) {
		httpReq.ContentLength = 0
	} else {
		httpReq.ContentLength = contentLength
	}

	// Set the Host header
	httpReq.Host = string(req.Header.Host())

	return httpReq, nil
}

func SetMetaHeaders(ctx *fiber.Ctx, meta map[string]string) {
	ctx.Response().Header.DisableNormalizing()
	for key, val := range meta {
		ctx.Response().Header.Set(fmt.Sprintf("X-Amz-Meta-%s", key), val)
	}
	ctx.Response().Header.EnableNormalizing()
}

func ParseUint(str string) (int32, error) {
	if str == "" {
		return 1000, nil
	}
	num, err := strconv.ParseUint(str, 10, 16)
	if err != nil {
		return 1000, s3err.GetAPIError(s3err.ErrInvalidMaxKeys)
	}
	return int32(num), nil
}

type CustomHeader struct {
	Key   string
	Value string
}

func SetResponseHeaders(ctx *fiber.Ctx, headers []CustomHeader) {
	for _, header := range headers {
		ctx.Set(header.Key, header.Value)
	}
}

func IsValidBucketName(bucket string) bool {
	if len(bucket) < 3 || len(bucket) > 63 {
		return false
	}
	// Checks to contain only digits, lowercase letters, dot, hyphen.
	// Checks to start and end with only digits and lowercase letters.
	if !bucketNameRegexp.MatchString(bucket) {
		return false
	}
	// Checks not to be a valid IP address
	if bucketNameIpRegexp.MatchString(bucket) {
		return false
	}
	return true
}

func includeHeader(hdr string, signedHdrs []string) bool {
	for _, shdr := range signedHdrs {
		if strings.EqualFold(hdr, shdr) {
			return true
		}
	}
	return false
}

func IsBigDataAction(ctx *fiber.Ctx) bool {
	if ctx.Method() == http.MethodPut && len(strings.Split(ctx.Path(), "/")) >= 3 {
		if !ctx.Request().URI().QueryArgs().Has("tagging") && ctx.Get("X-Amz-Copy-Source") == "" && !ctx.Request().URI().QueryArgs().Has("acl") {
			return true
		}
	}
	return false
}

func ValidateDate(date time.Time) error {
	now := time.Now().UTC()
	diff := date.Unix() - now.Unix()

	// Checks the dates difference to be less than a minute
	if diff > 60 {
		return s3err.APIError{
			Code:           "SignatureDoesNotMatch",
			Description:    fmt.Sprintf("Signature not yet current: %s is still later than %s", date.Format(iso8601Format), now.Format(iso8601Format)),
			HTTPStatusCode: http.StatusForbidden,
		}
	}
	if diff < -60 {
		return s3err.APIError{
			Code:           "SignatureDoesNotMatch",
			Description:    fmt.Sprintf("Signature expired: %s is now earlier than %s", date.Format(iso8601Format), now.Format(iso8601Format)),
			HTTPStatusCode: http.StatusForbidden,
		}
	}

	return nil
}