package abuseipdb

import (
	"bytes"
	"context"
	"encoding/csv"
	"encoding/json"
	"errors"
	"fmt"
	"html"
	"io"
	"mime/multipart"
	"net"
	"net/http"
	"net/url"
	"reflect"
	"sst.rievo.dev/go-abuseipdb/pkg/abuseipdb/rate"
	"strconv"
	"strings"
	"time"
)

const (
	Version          = "v2.0"
	defaultBaseURL   = "https://api.abuseipdb.com/api/v2/"
	defaultUserAgent = "go-abuseipdb/" + Version
)

type Client struct {
	client  *http.Client
	BaseURL *url.URL

	UserAgent string
	APIKey    string

	// ratelimit
	RateLimit *rate.Limit
}

func NewClient(client *http.Client) *Client {
	if client == nil {
		client = &http.Client{}
	}
	copiedClient := *client
	c := &Client{client: &copiedClient}
	c.initialize()
	return c
}

func (c *Client) AddApiKey(key string) {
	c.APIKey = key
}

func (c *Client) initialize() {
	if c.client == nil {
		c.client = &http.Client{}
	}
	if c.BaseURL == nil {
		c.BaseURL, _ = url.Parse(defaultBaseURL)
	}
	if c.UserAgent == "" {
		c.UserAgent = defaultUserAgent
	}
}

func (c *Client) NewRequest(method, urlStr string, parameter map[string]string, body io.Reader) (*http.Request, error) {
	if !strings.HasSuffix(c.BaseURL.Path, "/") {
		return nil, fmt.Errorf("BaseURL must have a trailing slash, but %q does not", c.BaseURL)
	}

	u, err := c.BaseURL.Parse(urlStr)
	if err != nil {
		return nil, err
	}

	req, err := http.NewRequest(method, u.String(), body)
	if err != nil {
		return nil, err
	}
	req.Header.Set("User-Agent", c.UserAgent)
	req.Header.Set("Accept", "application/json")
	req.Header.Set("Key", c.APIKey)

	q := req.URL.Query()
	for k, v := range parameter {
		q.Add(k, v)
	}
	req.URL.RawQuery = q.Encode()
	return req, nil
}

type errorResponse struct {
	Errors []struct {
		Detail string `json:"detail"`
		Status int    `json:"status"`
	} `json:"errors"`
}

func handleError(r *http.Response) error {
	if r.StatusCode == http.StatusTooManyRequests {
		return fmt.Errorf("too many requests, see: Client.RateLimit")
	}
	if r.StatusCode >= 400 {
		var errR *errorResponse
		err := json.NewDecoder(r.Body).Decode(&errR)
		if err != nil {
			return fmt.Errorf("unable to decode error message %d: %w", r.StatusCode, err)
		}
		return fmt.Errorf("abuseipdb error: %s", errR.Errors[0].Detail)
	}
	return nil
}

func (c *Client) Do(ctx context.Context, req *http.Request, v any) error {
	resp, err := c.client.Do(req.WithContext(ctx))
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	switch v := v.(type) {
	case nil:
	case io.Writer:
		_, err = io.Copy(v, resp.Body)
	default:
		decErr := json.NewDecoder(resp.Body).Decode(v)
		if decErr == io.EOF {
			decErr = nil // ignore EOF errors caused by empty response body
		}
		if decErr != nil {
			err = decErr
		}
	}
	return err
}

type CheckOptions struct {
	MaxAgeInDays int  `json:"maxAgeInDays,omitempty"`
	Verbose      bool `json:"verbose,omitempty"`
}

type CheckResult struct {
	Data struct {
		IpAddress            string              `json:"ipAddress"`
		IsPublic             bool                `json:"isPublic"`
		IpVersion            int                 `json:"ipVersion"`
		IsWhitelisted        bool                `json:"isWhitelisted"`
		AbuseConfidenceScore int                 `json:"abuseConfidenceScore"` // 100 spam, 0 ham
		CountryCode          string              `json:"countryCode"`
		CountryName          string              `json:"countryName,omitempty"`
		UsageType            string              `json:"usageType"`
		Isp                  string              `json:"isp"`
		Domain               string              `json:"domain"`
		Hostnames            []string            `json:"hostnames"`
		IsTor                bool                `json:"isTor"`
		TotalReports         int                 `json:"totalReports"`
		NumDistinctUsers     int                 `json:"numDistinctUsers"`
		LastReportedAt       time.Time           `json:"lastReportedAt"`
		Reports              []CheckResultReport `json:"reports,omitempty"`
	} `json:"data"`
}

type CheckResultReport struct {
	ReportedAt          time.Time `json:"reportedAt"`
	Comment             string    `json:"comment"`
	Categories          []int     `json:"categories"`
	ReporterId          int       `json:"reporterId"`
	ReporterCountryCode string    `json:"reporterCountryCode"`
	ReporterCountryName string    `json:"reporterCountryName"`
}

func (c *Client) Check(ctx context.Context, ip net.IP, opts *CheckOptions) (*CheckResult, error) {
	var endpoint = "check"
	ipAddress := html.EscapeString(ip.String())
	parameters := map[string]string{
		"ipAddress": ipAddress,
	}

	if opts != nil {
		if opts.MaxAgeInDays > 0 && opts.MaxAgeInDays <= 365 {
			parameters["maxAgeInDays"] = strconv.Itoa(opts.MaxAgeInDays)
		}
		if opts.Verbose {
			parameters["verbose"] = ""
		}
	}

	req, err := c.NewRequest(http.MethodGet, endpoint, parameters, nil)
	if err != nil {
		return nil, err
	}

	var result *CheckResult
	err = c.Do(ctx, req, result)
	if err != nil {
		return nil, err
	}
	return result, nil
}

type ReportsOptions struct {
	MaxAgeInDays int `json:"maxAgeInDays,omitempty"`
	Page         int `json:"page,omitempty"`
	PerPage      int `json:"perPage,omitempty"`
}

type ReportsResult struct {
	Data struct {
		Total           int                  `json:"total"`
		Page            int                  `json:"page"`
		Count           int                  `json:"count"`
		PerPage         int                  `json:"perPage"`
		LastPage        int                  `json:"lastPage"`
		NextPageUrl     string               `json:"nextPageUrl"`
		PreviousPageUrl string               `json:"previousPageUrl"`
		Results         []ReportResultReport `json:"results,omitempty"`
	} `json:"data"`
}
type ReportResultReport struct {
	ReportedAt          time.Time `json:"reportedAt"`
	Comment             string    `json:"comment"`
	Categories          []int     `json:"categories"`
	ReporterId          int       `json:"reporterId"`
	ReporterCountryCode string    `json:"reporterCountryCode"`
	ReporterCountryName string    `json:"reporterCountryName"`
}

func (c *Client) Reports(ctx context.Context, ip net.IP, opts *ReportsOptions) (*ReportsResult, error) {
	var endpoint = "reports"
	ipAddress := html.EscapeString(ip.String())
	parameters := map[string]string{
		"ipAddress": ipAddress,
	}

	if opts != nil {
		if opts.MaxAgeInDays > 0 && opts.MaxAgeInDays <= 365 {
			parameters["maxAgeInDays"] = strconv.Itoa(opts.MaxAgeInDays)
		}
		if opts.Page > 0 {
			parameters["page"] = strconv.Itoa(opts.Page)
		}
		if opts.PerPage > 0 && opts.PerPage <= 100 {
			parameters["perPage"] = strconv.Itoa(opts.PerPage)
		}
	}

	req, err := c.NewRequest(http.MethodGet, endpoint, parameters, nil)
	if err != nil {
		return nil, err
	}

	var result *ReportsResult
	err = c.Do(ctx, req, result)
	if err != nil {
		return nil, err
	}
	return result, nil
}

type BlacklistOptions struct {
	ConfidenceMinimum int      `json:"confidenceMinimum,omitempty"`
	Limit             int      `json:"limit,omitempty"`
	OnlyCountries     []string `json:"onlyCountries,omitempty"`
	ExceptCountries   []string `json:"exceptCountries,omitempty"`
	IpVersion         int      `json:"ipVersion,omitempty"`
}

type BlacklistResult struct {
	Meta struct {
		GeneratedAt time.Time `json:"generatedAt"`
	} `json:"meta"`
	Data []struct {
		IpAddress            string    `json:"ipAddress"`
		AbuseConfidenceScore int       `json:"abuseConfidenceScore,omitempty"`
		LastReportedAt       time.Time `json:"lastReportedAt"`
	} `json:"data"`
}

func handleBlacklistOptions(opts *BlacklistOptions) map[string]string {
	parameters := map[string]string{}
	if opts != nil {
		if opts.ConfidenceMinimum > 25 && opts.ConfidenceMinimum <= 100 {
			parameters["confidenceMinimum"] = strconv.Itoa(opts.ConfidenceMinimum)
		}
		if opts.Limit > 0 && opts.Limit <= 500_000 {
			parameters["limit"] = strconv.Itoa(opts.Limit)
		}
		if opts.OnlyCountries != nil && len(opts.OnlyCountries) > 0 {
			parameters["onlyCountries"] = strings.Join(opts.OnlyCountries, ",")
		}
		if opts.ExceptCountries != nil && len(opts.ExceptCountries) > 0 {
			parameters["exceptCountries"] = strings.Join(opts.ExceptCountries, ",")
		}
		if opts.IpVersion == 4 || opts.IpVersion == 6 {
			parameters["ipVersion"] = strconv.Itoa(opts.IpVersion)
		}
	}
	return parameters
}

func (c *Client) Blacklist(ctx context.Context, opts *BlacklistOptions) (*BlacklistResult, error) {
	var endpoint = "blacklist"

	parameters := handleBlacklistOptions(opts)

	req, err := c.NewRequest(http.MethodGet, endpoint, parameters, nil)
	if err != nil {
		return nil, err
	}

	var result *BlacklistResult
	err = c.Do(ctx, req, result)
	if err != nil {
		return nil, err
	}
	return result, nil
}

func (c *Client) BlacklistPlain(ctx context.Context, opts *BlacklistOptions) (io.Reader, error) {
	var endpoint = "blacklist"

	parameters := handleBlacklistOptions(opts)

	req, err := c.NewRequest(http.MethodGet, endpoint, parameters, nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Accept", "text/plain")

	resp, err := c.client.Do(req.WithContext(ctx))
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	var result *bytes.Buffer
	_, err = io.Copy(result, resp.Body)
	if err != nil {
		return nil, err
	}
	return result, nil
}

type ReportOptions struct {
	Categories []int      `json:"categories"`
	Comment    string     `json:"comment,omitempty"`
	Time       *time.Time `json:"timestamp,omitempty"`
}

type ReportResult struct {
	Data struct {
		IpAddress            string `json:"ipAddress"`
		AbuseConfidenceScore int    `json:"abuseConfidenceScore"`
	} `json:"data"`
}

func (c *Client) Report(ctx context.Context, ip net.IP, opts *ReportOptions) (*ReportsResult, error) {
	var endpoint = "report"

	ipAddress := html.EscapeString(ip.String())
	parameters := map[string]string{
		"ip": ipAddress,
	}

	if opts != nil {
		if opts.Categories != nil {
			categories := make([]string, len(opts.Categories))
			for _, category := range opts.Categories {
				categories = append(categories, strconv.Itoa(category))
			}
			parameters["categories"] = strings.Join(categories, ",")
		}
		if opts.Comment != "" {
			parameters["comment"] = opts.Comment
		}
		if opts.Time != nil {
			parameters["timestamp"] = opts.Time.Format(time.RFC3339)
		}
	}

	req, err := c.NewRequest(http.MethodGet, endpoint, parameters, nil)
	if err != nil {
		return nil, err
	}
	var result *ReportsResult
	err = c.Do(ctx, req, result)
	if err != nil {
		return nil, err
	}
	return result, nil
}

type CheckBlockOptions struct {
	MaxAgeInDays int `json:"maxAgeInDays,omitempty"`
}

type CheckBlockResult struct {
	Data struct {
		NetworkAddress   string `json:"networkAddress"`
		Netmask          string `json:"netmask"`
		MinAddress       string `json:"minAddress"`
		MaxAddress       string `json:"maxAddress"`
		NumPossibleHosts int    `json:"numPossibleHosts"`
		AddressSpaceDesc string `json:"addressSpaceDesc"`
		ReportedAddress  []struct {
			IpAddress            string    `json:"ipAddress"`
			NumReports           int       `json:"numReports"`
			MostRecentReport     time.Time `json:"mostRecentReport"`
			AbuseConfidenceScore int       `json:"abuseConfidenceScore"`
			CountryCode          string    `json:"countryCode"`
		} `json:"reportedAddress,omitempty"`
	} `json:"data"`
}

func (c *Client) CheckBlock(ctx context.Context, ipnNet net.IPNet, opts *CheckBlockOptions) (*CheckBlockResult, error) {
	var endpoint = "check-block"

	network := html.EscapeString(ipnNet.String())
	parameters := map[string]string{
		"network": network,
	}
	// TODO check network
	if opts != nil {
		if opts.MaxAgeInDays > 0 && opts.MaxAgeInDays <= 365 {
			parameters["maxAgeInDays"] = strconv.Itoa(opts.MaxAgeInDays)
		}
	}

	req, err := c.NewRequest(http.MethodGet, endpoint, parameters, nil)
	if err != nil {
		return nil, err
	}

	var result *CheckBlockResult
	err = c.Do(ctx, req, result)
	if err != nil {
		return nil, err
	}
	return result, nil
}

type BulkReportData struct {
	IpAddress  string    `csv:"IP"`
	Categories []int     `csv:"Categories"`
	ReportDate time.Time `csv:"ReportDate"`
	Comment    string    `csv:"Comment"`
}

type BulkReportDatas []BulkReportData

func (b *BulkReportDatas) getHeaders() []string {
	if b == nil || len(*b) == 0 {
		return nil
	}
	val := reflect.ValueOf((*b)[0])
	var headers []string
	for i := 0; i < val.Type().NumField(); i++ {
		t := val.Type().Field(i)
		fieldName := t.Name

		jsonTag := t.Tag.Get("csv")
		parts := strings.Split(jsonTag, ",")
		name := parts[0]
		if name == "" {
			name = fieldName
		}
		headers = append(headers, name)
	}
	return headers
}

func (b *BulkReportDatas) toSlice() [][]string {
	var slice [][]string
	if b == nil || len(*b) == 0 {
		return nil
	}
	for _, data := range *b {
		categories := make([]string, len(data.Categories))
		for i, category := range data.Categories {
			categories[i] = strconv.Itoa(category)
		}
		slice = append(slice, []string{
			data.IpAddress,
			strings.Join(categories, ","),
			data.ReportDate.Format(time.RFC3339),
			data.Comment,
		})
	}
	return slice
}

func (b *BulkReportDatas) Csv() io.Reader {
	result := &bytes.Buffer{}
	writer := csv.NewWriter(result)

	err := writer.WriteAll(append([][]string{b.getHeaders()}, b.toSlice()...))
	if err != nil {
		return nil
	}

	return result
}

func (b *BulkReportDatas) validate() error {
	if b == nil || len(*b) == 0 {
		return nil
	}

	for i, data := range *b {
		if len(data.Categories) == 0 {
			return fmt.Errorf("no categories found in BulkReportDatas entry %d", i)
		}
		if data.ReportDate.IsZero() {
			return fmt.Errorf("no report date found in BulkReportDatas entry %d", i)
		}
		if len(data.Comment) > 1_024 {
			return fmt.Errorf("comment is too long (%d bytes) for entry %d", len(data.Comment), i)
		}
	}
	return nil
}

type BulkReportResult struct {
	Data struct {
		SavedReports   int `json:"savedReports"`
		InvalidReports []struct {
			Error     string `json:"error"`
			Input     string `json:"input"`
			RowNumber int    `json:"rowNumber"`
		} `json:"invalidReports,omitempty"`
	} `json:"data"`
}

func (c *Client) BulkReport(ctx context.Context, data *BulkReportDatas) (*BulkReportResult, error) {
	var endpoint = "bulk-report"

	if data == nil || len(*data) == 0 {
		return nil, errors.New("bulk report: no data")
	}
	if err := data.validate(); err != nil {
		return nil, err
	}
	csvData := data.Csv()
	if csvData == nil {
		return nil, errors.New("bulk report: no csv data")
	}

	var requestBody bytes.Buffer
	writer := multipart.NewWriter(&requestBody)
	formFile, err := writer.CreateFormFile("csv", "data.csv")
	if err != nil {
		return nil, err
	}
	_, err = io.Copy(formFile, csvData)
	if err != nil {
		return nil, err
	}
	writer.Close()
	req, err := c.NewRequest(http.MethodGet, endpoint, nil, &requestBody)
	if err != nil {
		return nil, err
	}
	req.Header.Add("Content-Type", writer.FormDataContentType())

	var result *BulkReportResult
	err = c.Do(ctx, req, &result)
	if err != nil {
		return nil, err
	}
	return result, nil
}

type ClearAddressData struct {
	Data struct {
		NumReportsDeleted int `json:"numReportsDeleted"`
	} `json:"data"`
}

func (c *Client) ClearAddress(ctx context.Context, ip net.IP) (*ClearAddressData, error) {
	var endpoint = "clear-address"
	ipAddress := html.EscapeString(ip.String())
	parameters := map[string]string{
		"ipAddress": ipAddress,
	}

	req, err := c.NewRequest(http.MethodPost, endpoint, parameters, nil)
	if err != nil {
		return nil, err
	}
	var result *ClearAddressData
	err = c.Do(ctx, req, &result)
	if err != nil {
		return nil, err
	}
	return result, nil
}