package eventapi

import (
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"strconv"
	"time"

	"github.com/itworx/pulse/internal/auth"
	"github.com/itworx/pulse/internal/problem"
	"github.com/jackc/pgx/v5/pgxpool"
)

type Event struct {
	ID            string          `json:"id"`
	Type          string          `json:"type"`
	Severity      string          `json:"severity"`
	EntityID      *string         `json:"entityId,omitempty"`
	SourceID      *string         `json:"sourceId,omitempty"`
	OccurredAt    time.Time       `json:"occurredAt"`
	ReceivedAt    time.Time       `json:"receivedAt"`
	Summary       string          `json:"summary"`
	Attributes    json.RawMessage `json:"attributes"`
	CorrelationID *string         `json:"correlationId,omitempty"`
}

type Store interface {
	List(context.Context, int) ([]Event, error)
}

type PostgresStore struct{ Pool *pgxpool.Pool }

func (s PostgresStore) List(ctx context.Context, limit int) ([]Event, error) {
	if s.Pool == nil {
		return nil, errors.New("event database pool is nil")
	}
	rows, err := s.Pool.Query(ctx, `SELECT id::text,event_type,severity,entity_id::text,source_id::text,occurred_at,received_at,summary,attributes,correlation_id FROM events ORDER BY occurred_at DESC,id DESC LIMIT $1`, limit)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	items := make([]Event, 0, limit)
	for rows.Next() {
		var item Event
		if err := rows.Scan(&item.ID, &item.Type, &item.Severity, &item.EntityID, &item.SourceID, &item.OccurredAt, &item.ReceivedAt, &item.Summary, &item.Attributes, &item.CorrelationID); err != nil {
			return nil, err
		}
		items = append(items, item)
	}
	return items, rows.Err()
}

type Handler struct{ Store Store }

func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet || r.URL.Path != "/api/v1/events" {
		http.NotFound(w, r)
		return
	}
	if _, ok := auth.PrincipalFromContext(r.Context()); !ok {
		problem.Write(w, r, http.StatusUnauthorized, "UNAUTHORIZED", "Authentication required", "Authentication is required to read events.", nil)
		return
	}
	limit := 100
	if raw := r.URL.Query().Get("limit"); raw != "" {
		value, err := strconv.Atoi(raw)
		if err != nil || value < 1 || value > 100 {
			problem.Write(w, r, http.StatusBadRequest, "INVALID_LIMIT", "Invalid limit", "The event limit must be between 1 and 100.", nil)
			return
		}
		limit = value
	}
	items, err := h.Store.List(r.Context(), limit)
	if err != nil {
		if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
			return
		}
		problem.Write(w, r, http.StatusServiceUnavailable, "EVENTS_UNAVAILABLE", "Events unavailable", "Gebeurtenissen konden niet worden gelezen.", nil)
		return
	}
	w.Header().Set("Content-Type", "application/json")
	w.Header().Set("Cache-Control", "private, max-age=5")
	_ = json.NewEncoder(w).Encode(map[string]any{"items": items})
}