// Package dnsdumpster logic
package dnsdumpster

import (
	"context"
	"encoding/json"
	"fmt"
	"time"

	"github.com/projectdiscovery/subfinder/v2/pkg/subscraping"
)

type response struct {
	A []struct {
		Host string `json:"host"`
	} `json:"a"`
	Ns []struct {
		Host string `json:"host"`
	} `json:"ns"`
}

// Source is the passive scraping agent
type Source struct {
	apiKeys   []string
	timeTaken time.Duration
	errors    int
	results   int
	requests  int
	skipped   bool
}

// Run function returns all subdomains found with the service
func (s *Source) Run(ctx context.Context, domain string, session *subscraping.Session) <-chan subscraping.Result {
	results := make(chan subscraping.Result)
	s.errors = 0
	s.results = 0
	s.requests = 0

	go func() {
		defer func(startTime time.Time) {
			s.timeTaken = time.Since(startTime)
			close(results)
		}(time.Now())

		randomApiKey := subscraping.PickRandom(s.apiKeys, s.Name())
		if randomApiKey == "" {
			s.skipped = true
			return
		}

		s.requests++
		resp, err := session.Get(ctx, fmt.Sprintf("https://api.dnsdumpster.com/domain/%s", domain), "", map[string]string{"X-API-Key": randomApiKey})
		if err != nil {
			results <- subscraping.Result{Source: s.Name(), Type: subscraping.Error, Error: err}
			s.errors++
			session.DiscardHTTPResponse(resp)
			return
		}
		defer session.DiscardHTTPResponse(resp)

		var response response
		err = json.NewDecoder(resp.Body).Decode(&response)
		if err != nil {
			results <- subscraping.Result{Source: s.Name(), Type: subscraping.Error, Error: err}
			s.errors++
			session.DiscardHTTPResponse(resp)
			return
		}

		for _, record := range append(response.A, response.Ns...) {
			select {
			case <-ctx.Done():
				return
			case results <- subscraping.Result{Source: s.Name(), Type: subscraping.Subdomain, Value: record.Host}:
				s.results++
			}
		}

	}()

	return results
}

// Name returns the name of the source
func (s *Source) Name() string {
	return "dnsdumpster"
}

func (s *Source) IsDefault() bool {
	return true
}

func (s *Source) HasRecursiveSupport() bool {
	return false
}

func (s *Source) KeyRequirement() subscraping.KeyRequirement {
	return subscraping.RequiredKey
}

func (s *Source) NeedsKey() bool {
	return s.KeyRequirement() == subscraping.RequiredKey
}

func (s *Source) AddApiKeys(keys []string) {
	s.apiKeys = keys
}

func (s *Source) Statistics() subscraping.Statistics {
	return subscraping.Statistics{
		Errors:    s.errors,
		Results:   s.results,
		Requests:  s.requests,
		TimeTaken: s.timeTaken,
		Skipped:   s.skipped,
	}
}
