package api

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

type CronMetric struct {
	Timestamp     string  `json:"timestamp"`
	Source        string  `json:"source"`
	Hostname      string  `json:"hostname,omitempty"`
	Status        string  `json:"status,omitempty"`
	MemoryTotalMB float64 `json:"memory_total_mb,omitempty"`
	MemoryFreeMB  float64 `json:"memory_free_mb,omitempty"`
	MemoryAvailMB float64 `json:"memory_available_mb,omitempty"`
	MemoryUsedMB  float64 `json:"memory_used_mb,omitempty"`
	MemoryPercent float64 `json:"memory_percent,omitempty"`
	CpuLoad1m     float64 `json:"cpu_load_1m,omitempty"`
	CpuLoad5m     float64 `json:"cpu_load_5m,omitempty"`
	CpuLoad15m    float64 `json:"cpu_load_15m,omitempty"`
	DiskTotalGB   float64 `json:"disk_total_gb,omitempty"`
	DiskFreeGB    float64 `json:"disk_free_gb,omitempty"`
	DiskUsedGB    float64 `json:"disk_used_gb,omitempty"`
	UptimeSec     float64 `json:"uptime_sec,omitempty"`
	Notes         string  `json:"notes,omitempty"`
}

var (
	cronMetricMu      sync.RWMutex
	cronMetricHistory []CronMetric
	cronMetricMaxKeep = 240
)

func (s *Server) handleCronMetrics(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		cronMetricMu.RLock()
		history := append([]CronMetric(nil), cronMetricHistory...)
		cronMetricMu.RUnlock()
		latest := CronMetric{}
		if len(history) > 0 {
			latest = history[len(history)-1]
		}
		writeAnyJSON(w, http.StatusOK, map[string]any{
			"count":   len(history),
			"latest":  latest,
			"history": history,
		})
	case http.MethodPost:
		if !allowCronIngest(r) {
			writeJSONError(w, http.StatusUnauthorized, "invalid cron token")
			return
		}
		var payload map[string]any
		if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
			writeJSONError(w, http.StatusBadRequest, "invalid json payload")
			return
		}
		sample := normalizeCronMetric(payload)
		cronMetricMu.Lock()
		cronMetricHistory = append(cronMetricHistory, sample)
		if len(cronMetricHistory) > cronMetricMaxKeep {
			cronMetricHistory = append([]CronMetric(nil), cronMetricHistory[len(cronMetricHistory)-cronMetricMaxKeep:]...)
		}
		count := len(cronMetricHistory)
		cronMetricMu.Unlock()
		writeAnyJSON(w, http.StatusOK, map[string]any{"ok": true, "stored": count, "latest": sample})
	default:
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
	}
}

func allowCronIngest(r *http.Request) bool {
	expected := strings.TrimSpace(os.Getenv("CRON_TOKEN"))
	if expected == "" {
		return true
	}
	return strings.TrimSpace(r.Header.Get("X-Cron-Token")) == expected
}

func normalizeCronMetric(payload map[string]any) CronMetric {
	now := time.Now().UTC().Format(time.RFC3339)
	metric := CronMetric{
		Timestamp: now,
		Source:    textValue(payload, "source", "function", "name", "host", "hostname", "instance"),
		Hostname:  textValue(payload, "hostname", "host", "node", "instance"),
		Status:    textValue(payload, "status"),
		Notes:     textValue(payload, "notes", "note", "message"),
	}
	if metric.Source == "" {
		metric.Source = "cron"
	}

	metric.MemoryTotalMB = numberValue(payload, "memory_total_mb", "total_memory_mb", "mem_total_mb", "mem_total")
	metric.MemoryFreeMB = numberValue(payload, "memory_free_mb", "free_memory_mb", "mem_free_mb", "free_mb")
	metric.MemoryAvailMB = numberValue(payload, "memory_available_mb", "available_memory_mb", "mem_available_mb", "avail_memory_mb")
	metric.MemoryUsedMB = numberValue(payload, "memory_used_mb", "used_memory_mb", "mem_used_mb", "used_mb")
	metric.MemoryPercent = numberValue(payload, "memory_percent", "mem_percent", "memory_usage_percent")
	if metric.MemoryUsedMB == 0 && metric.MemoryTotalMB > 0 && metric.MemoryFreeMB > 0 {
		metric.MemoryUsedMB = metric.MemoryTotalMB - metric.MemoryFreeMB
	}
	if metric.MemoryAvailMB == 0 && metric.MemoryFreeMB > 0 {
		metric.MemoryAvailMB = metric.MemoryFreeMB
	}
	if metric.MemoryPercent == 0 && metric.MemoryTotalMB > 0 && metric.MemoryUsedMB > 0 {
		metric.MemoryPercent = (metric.MemoryUsedMB / metric.MemoryTotalMB) * 100
	}

	metric.CpuLoad1m = numberValue(payload, "cpu_load_1m", "loadavg_1m", "load_1m", "load1")
	metric.CpuLoad5m = numberValue(payload, "cpu_load_5m", "loadavg_5m", "load_5m", "load5")
	metric.CpuLoad15m = numberValue(payload, "cpu_load_15m", "loadavg_15m", "load_15m", "load15")

	metric.DiskTotalGB = numberValue(payload, "disk_total_gb", "total_disk_gb", "disk_total_mb", "disk_total")
	metric.DiskFreeGB = numberValue(payload, "disk_free_gb", "free_disk_gb", "disk_free_mb", "disk_free")
	metric.DiskUsedGB = numberValue(payload, "disk_used_gb", "used_disk_gb", "disk_used_mb", "disk_used")
	if metric.DiskUsedGB == 0 && metric.DiskTotalGB > 0 && metric.DiskFreeGB > 0 {
		metric.DiskUsedGB = metric.DiskTotalGB - metric.DiskFreeGB
	}

	if uptime := numberValue(payload, "uptime_sec", "uptime", "uptime_seconds"); uptime > 0 {
		metric.UptimeSec = uptime
	}
	if ts := textValue(payload, "timestamp", "ts", "collected_at"); ts != "" {
		metric.Timestamp = ts
	}
	return metric
}

func textValue(payload map[string]any, keys ...string) string {
	for _, key := range keys {
		if value, ok := payload[key]; ok {
			text := strings.TrimSpace(toString(value))
			if text != "" {
				return text
			}
		}
	}
	return ""
}

func numberValue(payload map[string]any, keys ...string) float64 {
	for _, key := range keys {
		if value, ok := payload[key]; ok {
			if number, ok := toFloat64(value); ok {
				return number
			}
		}
	}
	return 0
}

func toString(value any) string {
	switch v := value.(type) {
	case string:
		return v
	case []byte:
		return string(v)
	case float64:
		return strconv.FormatFloat(v, 'f', -1, 64)
	case float32:
		return strconv.FormatFloat(float64(v), 'f', -1, 32)
	case int:
		return strconv.FormatInt(int64(v), 10)
	case int64:
		return strconv.FormatInt(v, 10)
	case json.Number:
		return v.String()
	default:
		return ""
	}
}

func toFloat64(value any) (float64, bool) {
	switch v := value.(type) {
	case float64:
		return v, true
	case float32:
		return float64(v), true
	case int:
		return float64(v), true
	case int64:
		return float64(v), true
	case json.Number:
		f, err := v.Float64()
		return f, err == nil
	case string:
		if strings.TrimSpace(v) == "" {
			return 0, false
		}
		n, err := strconv.ParseFloat(strings.TrimSpace(v), 64)
		if err == nil {
			return n, true
		}
		return 0, false
	default:
		return 0, false
	}
}