package proxy

import (
	"context"
	"encoding/json"
	"net"
	"net/http"
	"strconv"
	"strings"
	"time"
)

const proxyAPIVersion = "1.0.0"

// RouteRegistrar is the minimal route-registration surface used by RegisterMonitoringRoutes.
//
//	mux := http.NewServeMux()
//	RegisterMonitoringRoutes(mux, p)
type RouteRegistrar interface {
	HandleFunc(pattern string, handler func(http.ResponseWriter, *http.Request))
}

// SummaryResponse is the /1/summary JSON body.
type SummaryResponse struct {
	Version   string              `json:"version"`
	Mode      string              `json:"mode"`
	Hashrate  HashrateResponse    `json:"hashrate"`
	Miners    MinersCountResponse `json:"miners"`
	Workers   uint64              `json:"workers"`
	Upstreams UpstreamResponse    `json:"upstreams"`
	Results   ResultsResponse     `json:"results"`
}

// HashrateResponse carries the per-window hashrate array.
type HashrateResponse struct {
	Total [6]float64 `json:"total"`
}

// MinersCountResponse carries current and peak miner counts.
type MinersCountResponse struct {
	Now uint64 `json:"now"`
	Max uint64 `json:"max"`
}

// UpstreamResponse carries pool connection state counts.
type UpstreamResponse struct {
	Active uint64  `json:"active"`
	Sleep  uint64  `json:"sleep"`
	Error  uint64  `json:"error"`
	Total  uint64  `json:"total"`
	Ratio  float64 `json:"ratio"`
}

// ResultsResponse carries share acceptance statistics.
type ResultsResponse struct {
	Accepted    uint64     `json:"accepted"`
	Rejected    uint64     `json:"rejected"`
	Invalid     uint64     `json:"invalid"`
	Expired     uint64     `json:"expired"`
	AvgTime     uint32     `json:"avg_time"`
	Latency     uint32     `json:"latency"`
	HashesTotal uint64     `json:"hashes_total"`
	Best        [10]uint64 `json:"best"`
}

func startHTTPServer(p *Proxy) {
	if p == nil || p.config == nil || !p.config.HTTP.Enabled || p.httpServer != nil {
		return
	}

	mux := http.NewServeMux()
	RegisterMonitoringRoutes(mux, p)

	address := net.JoinHostPort(p.config.HTTP.Host, strconv.Itoa(int(p.config.HTTP.Port)))
	listener, errorValue := net.Listen("tcp", address)
	if errorValue != nil {
		return
	}

	server := &http.Server{
		Handler: mux,
	}
	p.httpServer = server

	go func() {
		_ = server.Serve(listener)
	}()
}

func stopHTTPServer(p *Proxy) {
	if p == nil || p.httpServer == nil {
		return
	}

	server := p.httpServer
	p.httpServer = nil

	shutdownContext, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	_ = server.Shutdown(shutdownContext)
}

// RegisterMonitoringRoutes mounts the monitoring endpoints on any router with HandleFunc.
//
//	mux := http.NewServeMux()
//	RegisterMonitoringRoutes(mux, p)
func RegisterMonitoringRoutes(router RouteRegistrar, proxyValue *Proxy) {
	if router == nil || proxyValue == nil {
		return
	}

	router.HandleFunc("/1/summary", func(writer http.ResponseWriter, request *http.Request) {
		if !allowHTTPRequest(writer, request, proxyValue.HTTPConfig()) {
			return
		}
		summary := proxyValue.Summary()
		upstreams := proxyValue.Upstreams()
		ratio := 0.0
		if upstreams.Total > 0 {
			ratio = float64(proxyValue.CurrentMiners()) / float64(upstreams.Total)
		}
		response := SummaryResponse{
			Version: proxyAPIVersion,
			Mode:    proxyValue.Mode(),
			Hashrate: HashrateResponse{
				Total: summary.Hashrate,
			},
			Miners: MinersCountResponse{
				Now: proxyValue.CurrentMiners(),
				Max: proxyValue.MaxMiners(),
			},
			Workers: uint64(len(proxyValue.Workers())),
			Upstreams: UpstreamResponse{
				Active: upstreams.Active,
				Sleep:  upstreams.Sleep,
				Error:  upstreams.Error,
				Total:  upstreams.Total,
				Ratio:  ratio,
			},
			Results: ResultsResponse{
				Accepted:    summary.Accepted,
				Rejected:    summary.Rejected,
				Invalid:     summary.Invalid,
				Expired:     summary.Expired,
				AvgTime:     summary.AvgTime,
				Latency:     summary.AvgLatency,
				HashesTotal: summary.Hashes,
				Best:        summary.TopDiff,
			},
		}
		writeHTTPJSON(writer, response)
	})

	router.HandleFunc("/1/workers", func(writer http.ResponseWriter, request *http.Request) {
		if !allowHTTPRequest(writer, request, proxyValue.HTTPConfig()) {
			return
		}

		records := proxyValue.Workers()
		rows := make([][]interface{}, 0, len(records))
		for _, record := range records {
			rows = append(rows, []interface{}{
				record.Name,
				record.LastIP,
				record.Connections,
				record.Accepted,
				record.Rejected,
				record.Invalid,
				record.Hashes,
				record.LastHashAt.Unix(),
				record.Hashrate(60),
				record.Hashrate(600),
				record.Hashrate(3600),
				record.Hashrate(43200),
				record.Hashrate(86400),
			})
		}

		writeHTTPJSON(writer, map[string]interface{}{
			"mode":    proxyValue.WorkersMode(),
			"workers": rows,
		})
	})

	router.HandleFunc("/1/miners", func(writer http.ResponseWriter, request *http.Request) {
		if !allowHTTPRequest(writer, request, proxyValue.HTTPConfig()) {
			return
		}

		miners := proxyValue.Miners()
		rows := make([][]interface{}, 0, len(miners))
		for _, miner := range miners {
			ip := ""
			if remote := miner.RemoteAddr(); remote != nil {
				ip = remote.String()
			}
			rows = append(rows, []interface{}{
				miner.ID(),
				ip,
				miner.TX(),
				miner.RX(),
				miner.State(),
				miner.Diff(),
				miner.User(),
				"********",
				miner.RigID(),
				miner.Agent(),
			})
		}

		writeHTTPJSON(writer, map[string]interface{}{
			"format": []string{"id", "ip", "tx", "rx", "state", "diff", "user", "password", "rig_id", "agent"},
			"miners": rows,
		})
	})
}

func allowHTTPRequest(writer http.ResponseWriter, request *http.Request, config HTTPConfig) bool {
	if request == nil {
		return false
	}

	if config.AccessToken != "" {
		header := request.Header.Get("Authorization")
		prefix := "Bearer "
		if !strings.HasPrefix(header, prefix) || strings.TrimSpace(strings.TrimPrefix(header, prefix)) != config.AccessToken {
			writer.Header().Set("WWW-Authenticate", "Bearer")
			http.Error(writer, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
			return false
		}
	}

	if config.Restricted && request.Method != http.MethodGet {
		http.Error(writer, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
		return false
	}

	return true
}

func writeHTTPJSON(writer http.ResponseWriter, value interface{}) {
	writer.Header().Set("Content-Type", "application/json")
	_ = json.NewEncoder(writer).Encode(value)
}