package main

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"log"
	"net"
	"net/http"
	"strconv"
	"strings"
	"sync"
	"time"
	"unicode/utf8"
)

// maxReportMessageLen is the maximum length of the free-text message a user
// can attach to a report.
const maxReportMessageLen = 300

// reportTypeLabels maps the report types accepted by the API to their
// human-readable label used in notifications.
var reportTypeLabels = map[string]string{
	"offline":   "Repeater is offline",
	"frequency": "Frequency is incorrect",
	"callsign":  "Callsign has changed",
	"other":     "Other",
}

func reportTypeLabel(t string) string {
	if label, ok := reportTypeLabels[t]; ok {
		return label
	}
	return t
}

type UserReport struct {
	ID         int64   `json:"id"`
	CreatedAt  string  `json:"created_at"`
	RepeaterID int     `json:"repeater_id"`
	Callsign   string  `json:"callsign"`
	ReportType string  `json:"report_type"`
	Message    string  `json:"message"`
	Status     string  `json:"status"`
	ResolvedAt *string `json:"resolved_at"`
}

type reportsResponse struct {
	Reports []UserReport `json:"reports"`
	Total   int          `json:"total"`
	Open    int          `json:"open"`
}

// === Public API ===

func handleCreateReport(db *sql.DB, notifier *ntfyNotifier) http.HandlerFunc {
	limiter := newIPRateLimiter(5, time.Hour)

	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, `{"error":"method not allowed"}`, http.StatusMethodNotAllowed)
			return
		}

		var payload struct {
			RepeaterID int    `json:"repeater_id"`
			ReportType string `json:"report_type"`
			Message    string `json:"message"`
		}
		r.Body = http.MaxBytesReader(w, r.Body, 4096)
		if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
			http.Error(w, `{"error":"invalid request body"}`, http.StatusBadRequest)
			return
		}

		if _, ok := reportTypeLabels[payload.ReportType]; !ok {
			http.Error(w, `{"error":"invalid report type"}`, http.StatusBadRequest)
			return
		}

		message := strings.TrimSpace(payload.Message)
		if utf8.RuneCountInString(message) > maxReportMessageLen {
			http.Error(w, `{"error":"message too long"}`, http.StatusBadRequest)
			return
		}
		if payload.ReportType == "other" && message == "" {
			http.Error(w, `{"error":"message required"}`, http.StatusBadRequest)
			return
		}

		rpt, err := queryRepeaterByID(db, payload.RepeaterID)
		if err != nil || rpt == nil {
			http.Error(w, `{"error":"repeater not found"}`, http.StatusNotFound)
			return
		}

		// Only accepted reports count against the quota, so a user who mistypes
		// the form does not lock themselves out.
		if !limiter.allow(clientIP(r)) {
			http.Error(w, `{"error":"too many reports, please try again later"}`, http.StatusTooManyRequests)
			return
		}

		report := UserReport{
			RepeaterID: rpt.ID,
			Callsign:   rpt.Callsign,
			ReportType: payload.ReportType,
			Message:    message,
			Status:     "open",
		}

		var createdAt time.Time
		err = db.QueryRow(
			`INSERT INTO user_reports (repeater_id, callsign, report_type, message)
			 VALUES ($1, $2, $3, $4) RETURNING id, created_at`,
			report.RepeaterID, report.Callsign, report.ReportType, report.Message,
		).Scan(&report.ID, &createdAt)
		if err != nil {
			log.Printf("reports: insert failed for repeater %d: %v", report.RepeaterID, err)
			http.Error(w, `{"error":"could not store report"}`, http.StatusInternalServerError)
			return
		}
		report.CreatedAt = createdAt.Format("2006-01-02 15:04:05")

		insertChangelog(db, ChangelogEntry{
			RepeaterID:  report.RepeaterID,
			Callsign:    report.Callsign,
			Source:      "user",
			Action:      "report",
			Description: "User report: " + reportTypeLabel(report.ReportType),
			NewValues: map[string]interface{}{
				"report_type": report.ReportType,
				"message":     report.Message,
			},
		})

		notifier.notifyReport(report)

		w.Header().Set("Content-Type", "application/json")
		fmt.Fprintf(w, `{"ok":true,"id":%d}`, report.ID)
	}
}

// === Admin API ===

func handleAdminReports(db *sql.DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodGet {
			http.Error(w, `{"error":"method not allowed"}`, http.StatusMethodNotAllowed)
			return
		}

		status := r.URL.Query().Get("status")
		if status != "open" && status != "resolved" {
			status = ""
		}

		limit := 200
		if v := r.URL.Query().Get("limit"); v != "" {
			if p, err := strconv.Atoi(v); err == nil && p > 0 && p <= 500 {
				limit = p
			}
		}

		query := `SELECT id, created_at, repeater_id, callsign, report_type, message, status, resolved_at
			 FROM user_reports`
		args := []interface{}{}
		if status != "" {
			query += ` WHERE status = $1`
			args = append(args, status)
		}
		query += ` ORDER BY created_at DESC LIMIT ` + strconv.Itoa(limit)

		rows, err := db.Query(query, args...)
		if err != nil {
			log.Printf("admin reports: query failed: %v", err)
			http.Error(w, `{"error":"query failed"}`, http.StatusInternalServerError)
			return
		}
		defer rows.Close()

		reports := []UserReport{}
		for rows.Next() {
			var rep UserReport
			var createdAt time.Time
			var resolvedAt *time.Time
			if err := rows.Scan(&rep.ID, &createdAt, &rep.RepeaterID, &rep.Callsign,
				&rep.ReportType, &rep.Message, &rep.Status, &resolvedAt); err != nil {
				continue
			}
			rep.CreatedAt = createdAt.Format("2006-01-02 15:04:05")
			if resolvedAt != nil {
				formatted := resolvedAt.Format("2006-01-02 15:04:05")
				rep.ResolvedAt = &formatted
			}
			reports = append(reports, rep)
		}

		var total, open int
		db.QueryRow(`SELECT COUNT(*), COUNT(*) FILTER (WHERE status = 'open') FROM user_reports`).Scan(&total, &open)

		w.Header().Set("Content-Type", "application/json")
		json.NewEncoder(w).Encode(reportsResponse{Reports: reports, Total: total, Open: open})
	}
}

func handleAdminUpdateReport(db *sql.DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPut {
			http.Error(w, `{"error":"method not allowed"}`, http.StatusMethodNotAllowed)
			return
		}

		var payload struct {
			ID     int64  `json:"id"`
			Status string `json:"status"`
		}
		if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
			http.Error(w, `{"error":"invalid request body"}`, http.StatusBadRequest)
			return
		}
		if payload.ID <= 0 {
			http.Error(w, `{"error":"missing report id"}`, http.StatusBadRequest)
			return
		}
		if payload.Status != "open" && payload.Status != "resolved" {
			http.Error(w, `{"error":"status must be open or resolved"}`, http.StatusBadRequest)
			return
		}

		var resolvedAt interface{}
		if payload.Status == "resolved" {
			resolvedAt = time.Now()
		}

		_, err := db.Exec(`UPDATE user_reports SET status = $1, resolved_at = $2 WHERE id = $3`,
			payload.Status, resolvedAt, payload.ID)
		if err != nil {
			log.Printf("admin reports: status update failed for %d: %v", payload.ID, err)
			http.Error(w, `{"error":"update failed"}`, http.StatusInternalServerError)
			return
		}

		w.Header().Set("Content-Type", "application/json")
		w.Write([]byte(`{"ok":true}`))
	}
}

// handleAdminTestNotification publishes a test push so ntfy credentials can be
// verified without filing a report. Unlike the report path it waits for the
// result and returns the upstream error verbatim.
func handleAdminTestNotification(notifier *ntfyNotifier) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodPost {
			http.Error(w, `{"error":"method not allowed"}`, http.StatusMethodNotAllowed)
			return
		}

		w.Header().Set("Content-Type", "application/json")

		if notifier == nil {
			w.WriteHeader(http.StatusServiceUnavailable)
			w.Write([]byte(`{"error":"ntfy is not configured (NTFY_URL and NTFY_TOPIC must be set)"}`))
			return
		}

		if err := notifier.sendTest(); err != nil {
			log.Printf("ntfy: test notification failed: %v", err)
			w.WriteHeader(http.StatusBadGateway)
			json.NewEncoder(w).Encode(map[string]string{
				"error": err.Error(),
				"url":   notifier.url,
			})
			return
		}

		json.NewEncoder(w).Encode(map[string]interface{}{"ok": true, "url": notifier.url})
	}
}

func handleAdminDeleteReport(db *sql.DB) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if r.Method != http.MethodDelete {
			http.Error(w, `{"error":"method not allowed"}`, http.StatusMethodNotAllowed)
			return
		}

		id, err := strconv.ParseInt(r.URL.Query().Get("id"), 10, 64)
		if err != nil || id <= 0 {
			http.Error(w, `{"error":"missing or invalid id"}`, http.StatusBadRequest)
			return
		}

		if _, err := db.Exec(`DELETE FROM user_reports WHERE id = $1`, id); err != nil {
			log.Printf("admin reports: delete failed for %d: %v", id, err)
			http.Error(w, `{"error":"delete failed"}`, http.StatusInternalServerError)
			return
		}

		w.Header().Set("Content-Type", "application/json")
		w.Write([]byte(`{"ok":true}`))
	}
}

// === Rate limiting ===

// ipRateLimiter allows at most `limit` events per client IP within a sliding
// window. It keeps state in memory only — restarts reset all counters.
type ipRateLimiter struct {
	mu     sync.Mutex
	hits   map[string][]time.Time
	limit  int
	window time.Duration
	lastGC time.Time
}

func newIPRateLimiter(limit int, window time.Duration) *ipRateLimiter {
	return &ipRateLimiter{
		hits:   make(map[string][]time.Time),
		limit:  limit,
		window: window,
		lastGC: time.Now(),
	}
}

func (l *ipRateLimiter) allow(ip string) bool {
	now := time.Now()
	cutoff := now.Add(-l.window)

	l.mu.Lock()
	defer l.mu.Unlock()

	if now.Sub(l.lastGC) > l.window {
		for key, times := range l.hits {
			if len(prune(times, cutoff)) == 0 {
				delete(l.hits, key)
			}
		}
		l.lastGC = now
	}

	recent := prune(l.hits[ip], cutoff)
	if len(recent) >= l.limit {
		l.hits[ip] = recent
		return false
	}

	l.hits[ip] = append(recent, now)
	return true
}

func prune(times []time.Time, cutoff time.Time) []time.Time {
	kept := times[:0]
	for _, t := range times {
		if t.After(cutoff) {
			kept = append(kept, t)
		}
	}
	return kept
}

// clientIP returns the caller's IP, honouring the forwarding headers set by a
// reverse proxy. Used for rate limiting only — never stored.
func clientIP(r *http.Request) string {
	if fwd := r.Header.Get("X-Forwarded-For"); fwd != "" {
		if first, _, found := strings.Cut(fwd, ","); found {
			return strings.TrimSpace(first)
		}
		return strings.TrimSpace(fwd)
	}
	if real := r.Header.Get("X-Real-IP"); real != "" {
		return strings.TrimSpace(real)
	}
	if host, _, err := net.SplitHostPort(r.RemoteAddr); err == nil {
		return host
	}
	return r.RemoteAddr
}