package admin

import (
	"errors"
	"fmt"
	"io"
	"net/http"
	"strconv"
	"strings"
	"time"

	"github.com/Wei-Shaw/sub2api/internal/pkg/response"
	"github.com/Wei-Shaw/sub2api/internal/server/middleware"
	"github.com/Wei-Shaw/sub2api/internal/service"
	"github.com/gin-gonic/gin"
)

type OpsHandler struct {
	opsService *service.OpsService
}

const (
	opsListViewErrors   = "errors"
	opsListViewExcluded = "excluded"
	opsListViewAll      = "all"
)

func parseOpsViewParam(c *gin.Context) string {
	if c == nil {
		return ""
	}
	v := strings.ToLower(strings.TrimSpace(c.Query("view")))
	switch v {
	case "", opsListViewErrors:
		return opsListViewErrors
	case opsListViewExcluded:
		return opsListViewExcluded
	case opsListViewAll:
		return opsListViewAll
	default:
		return opsListViewErrors
	}
}

func NewOpsHandler(opsService *service.OpsService) *OpsHandler {
	return &OpsHandler{opsService: opsService}
}

// GetErrorLogs lists ops error logs.
// GET /api/v1/admin/ops/errors
func (h *OpsHandler) GetErrorLogs(c *gin.Context) {
	if h.opsService == nil {
		response.Error(c, http.StatusServiceUnavailable, "Ops service not available")
		return
	}
	if err := h.opsService.RequireMonitoringEnabled(c.Request.Context()); err != nil {
		response.ErrorFrom(c, err)
		return
	}

	page, pageSize := response.ParsePagination(c)
	// Ops list can be larger than standard admin tables.
	if pageSize > 500 {
		pageSize = 500
	}

	startTime, endTime, err := parseOpsTimeRange(c, "1h")
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	filter := &service.OpsErrorLogFilter{
		Page:     page,
		PageSize: pageSize,
	}
	if !startTime.IsZero() {
		filter.StartTime = &startTime
	}
	if !endTime.IsZero() {
		filter.EndTime = &endTime
	}

	if platform := strings.TrimSpace(c.Query("platform")); platform != "" {
		filter.Platform = platform
	}
	if v := strings.TrimSpace(c.Query("group_id")); v != "" {
		id, err := strconv.ParseInt(v, 10, 64)
		if err != nil || id <= 0 {
			response.BadRequest(c, "Invalid group_id")
			return
		}
		filter.GroupID = &id
	}
	if v := strings.TrimSpace(c.Query("account_id")); v != "" {
		id, err := strconv.ParseInt(v, 10, 64)
		if err != nil || id <= 0 {
			response.BadRequest(c, "Invalid account_id")
			return
		}
		filter.AccountID = &id
	}
	if phase := strings.TrimSpace(c.Query("phase")); phase != "" {
		filter.Phase = phase
	}
	if owner := strings.TrimSpace(c.Query("error_owner")); owner != "" {
		filter.Owner = owner
	}
	if source := strings.TrimSpace(c.Query("error_source")); source != "" {
		filter.Source = source
	}
	filter.View = parseOpsViewParam(c)
	if v := strings.TrimSpace(c.Query("resolved")); v != "" {
		switch strings.ToLower(v) {
		case "1", "true", "yes":
			b := true
			filter.Resolved = &b
		case "0", "false", "no":
			b := false
			filter.Resolved = &b
		default:
			response.BadRequest(c, "Invalid resolved")
			return
		}
	}
	if q := strings.TrimSpace(c.Query("q")); q != "" {
		filter.Query = q
	}
	if statusCodesStr := strings.TrimSpace(c.Query("status_codes")); statusCodesStr != "" {
		parts := strings.Split(statusCodesStr, ",")
		out := make([]int, 0, len(parts))
		for _, part := range parts {
			p := strings.TrimSpace(part)
			if p == "" {
				continue
			}
			n, err := strconv.Atoi(p)
			if err != nil || n < 0 {
				response.BadRequest(c, "Invalid status_codes")
				return
			}
			out = append(out, n)
		}
		filter.StatusCodes = out
	}

	result, err := h.opsService.GetErrorLogs(c.Request.Context(), filter)
	if err != nil {
		response.ErrorFrom(c, err)
		return
	}

	response.Paginated(c, result.Errors, int64(result.Total), result.Page, result.PageSize)
}

// GetErrorLogByID returns a single error log detail.
// GET /api/v1/admin/ops/errors/:id
func (h *OpsHandler) GetErrorLogByID(c *gin.Context) {
	if h.opsService == nil {
		response.Error(c, http.StatusServiceUnavailable, "Ops service not available")
		return
	}
	if err := h.opsService.RequireMonitoringEnabled(c.Request.Context()); err != nil {
		response.ErrorFrom(c, err)
		return
	}

	idStr := strings.TrimSpace(c.Param("id"))
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil || id <= 0 {
		response.BadRequest(c, "Invalid error id")
		return
	}

	detail, err := h.opsService.GetErrorLogByID(c.Request.Context(), id)
	if err != nil {
		response.ErrorFrom(c, err)
		return
	}

	response.Success(c, detail)
}

// ==================== New split endpoints ====================

// ListRequestErrors lists client-visible request errors.
// GET /api/v1/admin/ops/request-errors
func (h *OpsHandler) ListRequestErrors(c *gin.Context) {
	if h.opsService == nil {
		response.Error(c, http.StatusServiceUnavailable, "Ops service not available")
		return
	}
	if err := h.opsService.RequireMonitoringEnabled(c.Request.Context()); err != nil {
		response.ErrorFrom(c, err)
		return
	}

	page, pageSize := response.ParsePagination(c)
	if pageSize > 500 {
		pageSize = 500
	}
	startTime, endTime, err := parseOpsTimeRange(c, "1h")
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	filter := &service.OpsErrorLogFilter{Page: page, PageSize: pageSize}
	if !startTime.IsZero() {
		filter.StartTime = &startTime
	}
	if !endTime.IsZero() {
		filter.EndTime = &endTime
	}
	filter.View = parseOpsViewParam(c)
	filter.Phase = strings.TrimSpace(c.Query("phase"))
	filter.Owner = strings.TrimSpace(c.Query("error_owner"))
	filter.Source = strings.TrimSpace(c.Query("error_source"))
	filter.Query = strings.TrimSpace(c.Query("q"))

	// Force request errors: client-visible status >= 400.
	// buildOpsErrorLogsWhere already applies this for non-upstream phase.
	if strings.EqualFold(strings.TrimSpace(filter.Phase), "upstream") {
		filter.Phase = ""
	}

	if platform := strings.TrimSpace(c.Query("platform")); platform != "" {
		filter.Platform = platform
	}
	if v := strings.TrimSpace(c.Query("group_id")); v != "" {
		id, err := strconv.ParseInt(v, 10, 64)
		if err != nil || id <= 0 {
			response.BadRequest(c, "Invalid group_id")
			return
		}
		filter.GroupID = &id
	}
	if v := strings.TrimSpace(c.Query("account_id")); v != "" {
		id, err := strconv.ParseInt(v, 10, 64)
		if err != nil || id <= 0 {
			response.BadRequest(c, "Invalid account_id")
			return
		}
		filter.AccountID = &id
	}

	if v := strings.TrimSpace(c.Query("resolved")); v != "" {
		switch strings.ToLower(v) {
		case "1", "true", "yes":
			b := true
			filter.Resolved = &b
		case "0", "false", "no":
			b := false
			filter.Resolved = &b
		default:
			response.BadRequest(c, "Invalid resolved")
			return
		}
	}
	if statusCodesStr := strings.TrimSpace(c.Query("status_codes")); statusCodesStr != "" {
		parts := strings.Split(statusCodesStr, ",")
		out := make([]int, 0, len(parts))
		for _, part := range parts {
			p := strings.TrimSpace(part)
			if p == "" {
				continue
			}
			n, err := strconv.Atoi(p)
			if err != nil || n < 0 {
				response.BadRequest(c, "Invalid status_codes")
				return
			}
			out = append(out, n)
		}
		filter.StatusCodes = out
	}

	result, err := h.opsService.GetErrorLogs(c.Request.Context(), filter)
	if err != nil {
		response.ErrorFrom(c, err)
		return
	}
	response.Paginated(c, result.Errors, int64(result.Total), result.Page, result.PageSize)
}

// GetRequestError returns request error detail.
// GET /api/v1/admin/ops/request-errors/:id
func (h *OpsHandler) GetRequestError(c *gin.Context) {
	// same storage; just proxy to existing detail
	h.GetErrorLogByID(c)
}

// RetryRequestErrorClient retries the client request based on stored request body.
// POST /api/v1/admin/ops/request-errors/:id/retry-client
func (h *OpsHandler) RetryRequestErrorClient(c *gin.Context) {
	if h.opsService == nil {
		response.Error(c, http.StatusServiceUnavailable, "Ops service not available")
		return
	}
	if err := h.opsService.RequireMonitoringEnabled(c.Request.Context()); err != nil {
		response.ErrorFrom(c, err)
		return
	}

	subject, ok := middleware.GetAuthSubjectFromContext(c)
	if !ok || subject.UserID <= 0 {
		response.Error(c, http.StatusUnauthorized, "Unauthorized")
		return
	}

	idStr := strings.TrimSpace(c.Param("id"))
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil || id <= 0 {
		response.BadRequest(c, "Invalid error id")
		return
	}

	result, err := h.opsService.RetryError(c.Request.Context(), subject.UserID, id, service.OpsRetryModeClient, nil)
	if err != nil {
		response.ErrorFrom(c, err)
		return
	}
	response.Success(c, result)
}

// RetryRequestErrorUpstreamEvent retries a specific upstream attempt using captured upstream_request_body.
// POST /api/v1/admin/ops/request-errors/:id/upstream-errors/:idx/retry
func (h *OpsHandler) RetryRequestErrorUpstreamEvent(c *gin.Context) {
	if h.opsService == nil {
		response.Error(c, http.StatusServiceUnavailable, "Ops service not available")
		return
	}
	if err := h.opsService.RequireMonitoringEnabled(c.Request.Context()); err != nil {
		response.ErrorFrom(c, err)
		return
	}

	subject, ok := middleware.GetAuthSubjectFromContext(c)
	if !ok || subject.UserID <= 0 {
		response.Error(c, http.StatusUnauthorized, "Unauthorized")
		return
	}

	idStr := strings.TrimSpace(c.Param("id"))
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil || id <= 0 {
		response.BadRequest(c, "Invalid error id")
		return
	}

	idxStr := strings.TrimSpace(c.Param("idx"))
	idx, err := strconv.Atoi(idxStr)
	if err != nil || idx < 0 {
		response.BadRequest(c, "Invalid upstream idx")
		return
	}

	result, err := h.opsService.RetryUpstreamEvent(c.Request.Context(), subject.UserID, id, idx)
	if err != nil {
		response.ErrorFrom(c, err)
		return
	}
	response.Success(c, result)
}

// ResolveRequestError toggles resolved status.
// PUT /api/v1/admin/ops/request-errors/:id/resolve
func (h *OpsHandler) ResolveRequestError(c *gin.Context) {
	h.UpdateErrorResolution(c)
}

// ListUpstreamErrors lists independent upstream errors.
// GET /api/v1/admin/ops/upstream-errors
func (h *OpsHandler) ListUpstreamErrors(c *gin.Context) {
	if h.opsService == nil {
		response.Error(c, http.StatusServiceUnavailable, "Ops service not available")
		return
	}
	if err := h.opsService.RequireMonitoringEnabled(c.Request.Context()); err != nil {
		response.ErrorFrom(c, err)
		return
	}

	page, pageSize := response.ParsePagination(c)
	if pageSize > 500 {
		pageSize = 500
	}
	startTime, endTime, err := parseOpsTimeRange(c, "1h")
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	filter := &service.OpsErrorLogFilter{Page: page, PageSize: pageSize}
	if !startTime.IsZero() {
		filter.StartTime = &startTime
	}
	if !endTime.IsZero() {
		filter.EndTime = &endTime
	}

	filter.View = parseOpsViewParam(c)
	filter.Phase = "upstream"
	filter.Owner = "provider"
	filter.Source = strings.TrimSpace(c.Query("error_source"))
	filter.Query = strings.TrimSpace(c.Query("q"))

	if platform := strings.TrimSpace(c.Query("platform")); platform != "" {
		filter.Platform = platform
	}
	if v := strings.TrimSpace(c.Query("group_id")); v != "" {
		id, err := strconv.ParseInt(v, 10, 64)
		if err != nil || id <= 0 {
			response.BadRequest(c, "Invalid group_id")
			return
		}
		filter.GroupID = &id
	}
	if v := strings.TrimSpace(c.Query("account_id")); v != "" {
		id, err := strconv.ParseInt(v, 10, 64)
		if err != nil || id <= 0 {
			response.BadRequest(c, "Invalid account_id")
			return
		}
		filter.AccountID = &id
	}

	if v := strings.TrimSpace(c.Query("resolved")); v != "" {
		switch strings.ToLower(v) {
		case "1", "true", "yes":
			b := true
			filter.Resolved = &b
		case "0", "false", "no":
			b := false
			filter.Resolved = &b
		default:
			response.BadRequest(c, "Invalid resolved")
			return
		}
	}
	if statusCodesStr := strings.TrimSpace(c.Query("status_codes")); statusCodesStr != "" {
		parts := strings.Split(statusCodesStr, ",")
		out := make([]int, 0, len(parts))
		for _, part := range parts {
			p := strings.TrimSpace(part)
			if p == "" {
				continue
			}
			n, err := strconv.Atoi(p)
			if err != nil || n < 0 {
				response.BadRequest(c, "Invalid status_codes")
				return
			}
			out = append(out, n)
		}
		filter.StatusCodes = out
	}

	result, err := h.opsService.GetErrorLogs(c.Request.Context(), filter)
	if err != nil {
		response.ErrorFrom(c, err)
		return
	}
	response.Paginated(c, result.Errors, int64(result.Total), result.Page, result.PageSize)
}

// GetUpstreamError returns upstream error detail.
// GET /api/v1/admin/ops/upstream-errors/:id
func (h *OpsHandler) GetUpstreamError(c *gin.Context) {
	h.GetErrorLogByID(c)
}

// RetryUpstreamError retries upstream error using the original account_id.
// POST /api/v1/admin/ops/upstream-errors/:id/retry
func (h *OpsHandler) RetryUpstreamError(c *gin.Context) {
	if h.opsService == nil {
		response.Error(c, http.StatusServiceUnavailable, "Ops service not available")
		return
	}
	if err := h.opsService.RequireMonitoringEnabled(c.Request.Context()); err != nil {
		response.ErrorFrom(c, err)
		return
	}

	subject, ok := middleware.GetAuthSubjectFromContext(c)
	if !ok || subject.UserID <= 0 {
		response.Error(c, http.StatusUnauthorized, "Unauthorized")
		return
	}

	idStr := strings.TrimSpace(c.Param("id"))
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil || id <= 0 {
		response.BadRequest(c, "Invalid error id")
		return
	}

	result, err := h.opsService.RetryError(c.Request.Context(), subject.UserID, id, service.OpsRetryModeUpstream, nil)
	if err != nil {
		response.ErrorFrom(c, err)
		return
	}
	response.Success(c, result)
}

// ResolveUpstreamError toggles resolved status.
// PUT /api/v1/admin/ops/upstream-errors/:id/resolve
func (h *OpsHandler) ResolveUpstreamError(c *gin.Context) {
	h.UpdateErrorResolution(c)
}

// ==================== Existing endpoints ====================

// ListRequestDetails returns a request-level list (success + error) for drill-down.
// GET /api/v1/admin/ops/requests
func (h *OpsHandler) ListRequestDetails(c *gin.Context) {
	if h.opsService == nil {
		response.Error(c, http.StatusServiceUnavailable, "Ops service not available")
		return
	}
	if err := h.opsService.RequireMonitoringEnabled(c.Request.Context()); err != nil {
		response.ErrorFrom(c, err)
		return
	}

	page, pageSize := response.ParsePagination(c)
	if pageSize > 100 {
		pageSize = 100
	}

	startTime, endTime, err := parseOpsTimeRange(c, "1h")
	if err != nil {
		response.BadRequest(c, err.Error())
		return
	}

	filter := &service.OpsRequestDetailFilter{
		Page:      page,
		PageSize:  pageSize,
		StartTime: &startTime,
		EndTime:   &endTime,
	}

	filter.Kind = strings.TrimSpace(c.Query("kind"))
	filter.Platform = strings.TrimSpace(c.Query("platform"))
	filter.Model = strings.TrimSpace(c.Query("model"))
	filter.RequestID = strings.TrimSpace(c.Query("request_id"))
	filter.Query = strings.TrimSpace(c.Query("q"))
	filter.Sort = strings.TrimSpace(c.Query("sort"))

	if v := strings.TrimSpace(c.Query("user_id")); v != "" {
		id, err := strconv.ParseInt(v, 10, 64)
		if err != nil || id <= 0 {
			response.BadRequest(c, "Invalid user_id")
			return
		}
		filter.UserID = &id
	}
	if v := strings.TrimSpace(c.Query("api_key_id")); v != "" {
		id, err := strconv.ParseInt(v, 10, 64)
		if err != nil || id <= 0 {
			response.BadRequest(c, "Invalid api_key_id")
			return
		}
		filter.APIKeyID = &id
	}
	if v := strings.TrimSpace(c.Query("account_id")); v != "" {
		id, err := strconv.ParseInt(v, 10, 64)
		if err != nil || id <= 0 {
			response.BadRequest(c, "Invalid account_id")
			return
		}
		filter.AccountID = &id
	}
	if v := strings.TrimSpace(c.Query("group_id")); v != "" {
		id, err := strconv.ParseInt(v, 10, 64)
		if err != nil || id <= 0 {
			response.BadRequest(c, "Invalid group_id")
			return
		}
		filter.GroupID = &id
	}

	if v := strings.TrimSpace(c.Query("min_duration_ms")); v != "" {
		parsed, err := strconv.Atoi(v)
		if err != nil || parsed < 0 {
			response.BadRequest(c, "Invalid min_duration_ms")
			return
		}
		filter.MinDurationMs = &parsed
	}
	if v := strings.TrimSpace(c.Query("max_duration_ms")); v != "" {
		parsed, err := strconv.Atoi(v)
		if err != nil || parsed < 0 {
			response.BadRequest(c, "Invalid max_duration_ms")
			return
		}
		filter.MaxDurationMs = &parsed
	}

	out, err := h.opsService.ListRequestDetails(c.Request.Context(), filter)
	if err != nil {
		// Invalid sort/kind/platform etc should be a bad request; keep it simple.
		if strings.Contains(strings.ToLower(err.Error()), "invalid") {
			response.BadRequest(c, err.Error())
			return
		}
		response.Error(c, http.StatusInternalServerError, "Failed to list request details")
		return
	}

	response.Paginated(c, out.Items, out.Total, out.Page, out.PageSize)
}

type opsRetryRequest struct {
	Mode            string `json:"mode"`
	PinnedAccountID *int64 `json:"pinned_account_id"`
	Force           bool   `json:"force"`
}

type opsResolveRequest struct {
	Resolved bool `json:"resolved"`
}

// RetryErrorRequest retries a failed request using stored request_body.
// POST /api/v1/admin/ops/errors/:id/retry
func (h *OpsHandler) RetryErrorRequest(c *gin.Context) {
	if h.opsService == nil {
		response.Error(c, http.StatusServiceUnavailable, "Ops service not available")
		return
	}
	if err := h.opsService.RequireMonitoringEnabled(c.Request.Context()); err != nil {
		response.ErrorFrom(c, err)
		return
	}

	subject, ok := middleware.GetAuthSubjectFromContext(c)
	if !ok || subject.UserID <= 0 {
		response.Error(c, http.StatusUnauthorized, "Unauthorized")
		return
	}

	idStr := strings.TrimSpace(c.Param("id"))
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil || id <= 0 {
		response.BadRequest(c, "Invalid error id")
		return
	}

	req := opsRetryRequest{Mode: service.OpsRetryModeClient}
	if err := c.ShouldBindJSON(&req); err != nil && !errors.Is(err, io.EOF) {
		response.BadRequest(c, "Invalid request: "+err.Error())
		return
	}
	if strings.TrimSpace(req.Mode) == "" {
		req.Mode = service.OpsRetryModeClient
	}

	// Force flag is currently a UI-level acknowledgement. Server may still enforce safety constraints.
	_ = req.Force

	// Legacy endpoint safety: only allow retrying the client request here.
	// Upstream retries must go through the split endpoints.
	if strings.EqualFold(strings.TrimSpace(req.Mode), service.OpsRetryModeUpstream) {
		response.BadRequest(c, "upstream retry is not supported on this endpoint")
		return
	}

	result, err := h.opsService.RetryError(c.Request.Context(), subject.UserID, id, req.Mode, req.PinnedAccountID)
	if err != nil {
		response.ErrorFrom(c, err)
		return
	}

	response.Success(c, result)
}

// ListRetryAttempts lists retry attempts for an error log.
// GET /api/v1/admin/ops/errors/:id/retries
func (h *OpsHandler) ListRetryAttempts(c *gin.Context) {
	if h.opsService == nil {
		response.Error(c, http.StatusServiceUnavailable, "Ops service not available")
		return
	}
	if err := h.opsService.RequireMonitoringEnabled(c.Request.Context()); err != nil {
		response.ErrorFrom(c, err)
		return
	}

	idStr := strings.TrimSpace(c.Param("id"))
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil || id <= 0 {
		response.BadRequest(c, "Invalid error id")
		return
	}

	limit := 50
	if v := strings.TrimSpace(c.Query("limit")); v != "" {
		n, err := strconv.Atoi(v)
		if err != nil || n <= 0 {
			response.BadRequest(c, "Invalid limit")
			return
		}
		limit = n
	}

	items, err := h.opsService.ListRetryAttemptsByErrorID(c.Request.Context(), id, limit)
	if err != nil {
		response.ErrorFrom(c, err)
		return
	}
	response.Success(c, items)
}

// UpdateErrorResolution allows manual resolve/unresolve.
// PUT /api/v1/admin/ops/errors/:id/resolve
func (h *OpsHandler) UpdateErrorResolution(c *gin.Context) {
	if h.opsService == nil {
		response.Error(c, http.StatusServiceUnavailable, "Ops service not available")
		return
	}
	if err := h.opsService.RequireMonitoringEnabled(c.Request.Context()); err != nil {
		response.ErrorFrom(c, err)
		return
	}

	subject, ok := middleware.GetAuthSubjectFromContext(c)
	if !ok || subject.UserID <= 0 {
		response.Error(c, http.StatusUnauthorized, "Unauthorized")
		return
	}

	idStr := strings.TrimSpace(c.Param("id"))
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil || id <= 0 {
		response.BadRequest(c, "Invalid error id")
		return
	}

	var req opsResolveRequest
	if err := c.ShouldBindJSON(&req); err != nil {
		response.BadRequest(c, "Invalid request: "+err.Error())
		return
	}
	uid := subject.UserID
	if err := h.opsService.UpdateErrorResolution(c.Request.Context(), id, req.Resolved, &uid, nil); err != nil {
		response.ErrorFrom(c, err)
		return
	}
	response.Success(c, gin.H{"ok": true})
}

func parseOpsTimeRange(c *gin.Context, defaultRange string) (time.Time, time.Time, error) {
	startStr := strings.TrimSpace(c.Query("start_time"))
	endStr := strings.TrimSpace(c.Query("end_time"))

	parseTS := func(s string) (time.Time, error) {
		if s == "" {
			return time.Time{}, nil
		}
		if t, err := time.Parse(time.RFC3339Nano, s); err == nil {
			return t, nil
		}
		return time.Parse(time.RFC3339, s)
	}

	start, err := parseTS(startStr)
	if err != nil {
		return time.Time{}, time.Time{}, err
	}
	end, err := parseTS(endStr)
	if err != nil {
		return time.Time{}, time.Time{}, err
	}

	// start/end explicitly provided (even partially)
	if startStr != "" || endStr != "" {
		if end.IsZero() {
			end = time.Now()
		}
		if start.IsZero() {
			dur, _ := parseOpsDuration(defaultRange)
			start = end.Add(-dur)
		}
		if start.After(end) {
			return time.Time{}, time.Time{}, fmt.Errorf("invalid time range: start_time must be <= end_time")
		}
		if end.Sub(start) > 30*24*time.Hour {
			return time.Time{}, time.Time{}, fmt.Errorf("invalid time range: max window is 30 days")
		}
		return start, end, nil
	}

	// time_range fallback
	tr := strings.TrimSpace(c.Query("time_range"))
	if tr == "" {
		tr = defaultRange
	}
	dur, ok := parseOpsDuration(tr)
	if !ok {
		dur, _ = parseOpsDuration(defaultRange)
	}

	end = time.Now()
	start = end.Add(-dur)
	if end.Sub(start) > 30*24*time.Hour {
		return time.Time{}, time.Time{}, fmt.Errorf("invalid time range: max window is 30 days")
	}
	return start, end, nil
}

func parseOpsDuration(v string) (time.Duration, bool) {
	switch strings.TrimSpace(v) {
	case "5m":
		return 5 * time.Minute, true
	case "30m":
		return 30 * time.Minute, true
	case "1h":
		return time.Hour, true
	case "6h":
		return 6 * time.Hour, true
	case "24h":
		return 24 * time.Hour, true
	case "7d":
		return 7 * 24 * time.Hour, true
	case "30d":
		return 30 * 24 * time.Hour, true
	default:
		return 0, false
	}
}
