package telemetry

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"sort"
	"strings"
	"time"

	"github.com/shirou/gopsutil/v4/cpu"
	"github.com/shirou/gopsutil/v4/disk"
	"github.com/shirou/gopsutil/v4/host"
	gopsload "github.com/shirou/gopsutil/v4/load"
	"github.com/shirou/gopsutil/v4/mem"

	"git.hangman-lab.top/zhi/HarborForge.Monitor/internal/config"
)

const Version = "0.1.0"

type Payload struct {
	Identifier     string    `json:"identifier"`
	PluginVersion  string    `json:"plugin_version,omitempty"`
	Agents         []any     `json:"agents"`
	NginxInstalled bool      `json:"nginx_installed"`
	NginxSites     []string  `json:"nginx_sites"`
	CPUPct         float64   `json:"cpu_pct,omitempty"`
	MemPct         float64   `json:"mem_pct,omitempty"`
	DiskPct        float64   `json:"disk_pct,omitempty"`
	SwapPct        float64   `json:"swap_pct,omitempty"`
	LoadAvg        []float64 `json:"load_avg,omitempty"`
	UptimeSeconds  uint64    `json:"uptime_seconds,omitempty"`

	// Optional OpenClaw metadata, enriched from plugin bridge.
	// These fields are omitted if no plugin data is available.
	OpenClawVersion string `json:"openclaw_version,omitempty"`
}

func BuildPayload(ctx context.Context, cfg config.Config) (Payload, error) {
	payload := Payload{
		Identifier:    cfg.Identifier,
		PluginVersion: Version,
		Agents:        []any{},
		NginxSites:    []string{},
	}

	cpuPct, err := cpu.PercentWithContext(ctx, time.Second, false)
	if err == nil && len(cpuPct) > 0 {
		payload.CPUPct = round1(cpuPct[0])
	}

	vm, err := mem.VirtualMemoryWithContext(ctx)
	if err == nil {
		payload.MemPct = round1(vm.UsedPercent)
	}

	diskPath := cfg.RootFS
	if diskPath == "" {
		diskPath = "/"
	}
	diskUsage, err := disk.UsageWithContext(ctx, diskPath)
	if err == nil {
		payload.DiskPct = round1(diskUsage.UsedPercent)
	}

	swapUsage, err := mem.SwapMemoryWithContext(ctx)
	if err == nil {
		payload.SwapPct = round1(swapUsage.UsedPercent)
	}

	avg, err := gopsload.AvgWithContext(ctx)
	if err == nil {
		payload.LoadAvg = []float64{round2(avg.Load1), round2(avg.Load5), round2(avg.Load15)}
	}

	hostInfo, err := host.InfoWithContext(ctx)
	if err == nil {
		payload.UptimeSeconds = hostInfo.Uptime
	}

	nginxInstalled, nginxSites, err := detectNginx(cfg.RootFS)
	if err == nil {
		payload.NginxInstalled = nginxInstalled
		payload.NginxSites = nginxSites
	}

	return payload, nil
}

func Send(ctx context.Context, client *http.Client, cfg config.Config, payload Payload) error {
	body, err := json.Marshal(payload)
	if err != nil {
		return fmt.Errorf("marshal payload: %w", err)
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, strings.TrimRight(cfg.BackendURL, "/")+"/monitor/server/heartbeat", strings.NewReader(string(body)))
	if err != nil {
		return fmt.Errorf("build request: %w", err)
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("X-API-Key", cfg.APIKey)

	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("send request: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return fmt.Errorf("heartbeat failed with status %s", resp.Status)
	}
	return nil
}

func detectNginx(rootFS string) (bool, []string, error) {
	installed := false
	if rootFS == "" {
		if _, err := exec.LookPath("nginx"); err == nil {
			installed = true
		}
	}
	for _, path := range []string{
		rootPath(rootFS, "/etc/nginx/nginx.conf"),
		rootPath(rootFS, "/usr/local/etc/nginx/nginx.conf"),
		rootPath(rootFS, "/opt/homebrew/etc/nginx/nginx.conf"),
		rootPath(rootFS, "/usr/sbin/nginx"),
		rootPath(rootFS, "/usr/bin/nginx"),
	} {
		if _, err := os.Stat(path); err == nil {
			installed = true
			break
		}
	}
	if !installed {
		return false, []string{}, nil
	}

	dir := rootPath(rootFS, "/etc/nginx/sites-enabled")
	entries, err := os.ReadDir(dir)
	if err != nil {
		if os.IsNotExist(err) {
			return true, []string{}, nil
		}
		return true, nil, fmt.Errorf("read nginx sites-enabled: %w", err)
	}

	sites := make([]string, 0, len(entries))
	for _, entry := range entries {
		name := entry.Name()
		fullPath := filepath.Join(dir, name)
		if entry.Type()&os.ModeSymlink != 0 {
			if target, err := os.Readlink(fullPath); err == nil {
				name = fmt.Sprintf("%s -> %s", name, target)
			}
		}
		sites = append(sites, name)
	}
	sort.Strings(sites)
	return true, sites, nil
}

func round1(v float64) float64 {
	return float64(int(v*10+0.5)) / 10
}

func round2(v float64) float64 {
	return float64(int(v*100+0.5)) / 100
}

func rootPath(rootFS, path string) string {
	if rootFS == "" || rootFS == "/" {
		return path
	}
	return filepath.Join(rootFS, strings.TrimPrefix(path, "/"))
}