package handler

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/url"
	"vctp/components/views"
	"vctp/internal/report"

	"github.com/a-h/templ"
)

// SnapshotHourlyList renders the hourly snapshot list page.
// @Summary List hourly snapshots
// @Description Lists hourly inventory snapshot tables.
// @Tags snapshots
// @Produce text/html
// @Success 200 {string} string "HTML page"
// @Failure 500 {string} string "Server error"
// @Router /snapshots/hourly [get]
func (h *Handler) SnapshotHourlyList(w http.ResponseWriter, r *http.Request) {
	h.renderSnapshotList(w, r, "hourly", "Hourly Inventory Snapshots", views.SnapshotHourlyList)
}

// SnapshotDailyList renders the daily snapshot list page.
// @Summary List daily snapshots
// @Description Lists daily summary snapshot tables.
// @Tags snapshots
// @Produce text/html
// @Success 200 {string} string "HTML page"
// @Failure 500 {string} string "Server error"
// @Router /snapshots/daily [get]
func (h *Handler) SnapshotDailyList(w http.ResponseWriter, r *http.Request) {
	h.renderSnapshotList(w, r, "daily", "Daily Inventory Snapshots", views.SnapshotDailyList)
}

// SnapshotMonthlyList renders the monthly snapshot list page.
// @Summary List monthly snapshots
// @Description Lists monthly summary snapshot tables.
// @Tags snapshots
// @Produce text/html
// @Success 200 {string} string "HTML page"
// @Failure 500 {string} string "Server error"
// @Router /snapshots/monthly [get]
func (h *Handler) SnapshotMonthlyList(w http.ResponseWriter, r *http.Request) {
	h.renderSnapshotList(w, r, "monthly", "Monthly Inventory Snapshots", views.SnapshotMonthlyList)
}

// SnapshotReportDownload streams a snapshot table as XLSX.
// @Summary Download snapshot report
// @Description Downloads a snapshot table as an XLSX file.
// @Tags snapshots
// @Produce application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
// @Param table query string true "Snapshot table name"
// @Success 200 {file} file "Snapshot XLSX report"
// @Failure 400 {object} map[string]string "Invalid request"
// @Failure 500 {object} map[string]string "Server error"
// @Router /api/report/snapshot [get]
func (h *Handler) SnapshotReportDownload(w http.ResponseWriter, r *http.Request) {
	ctx := context.Background()
	tableName := r.URL.Query().Get("table")
	if tableName == "" {
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusBadRequest)
		json.NewEncoder(w).Encode(map[string]string{
			"status":  "ERROR",
			"message": "Missing table parameter",
		})
		return
	}

	reportData, err := report.CreateTableReport(h.Logger, h.Database, ctx, tableName)
	if err != nil {
		h.Logger.Error("Failed to create snapshot report", "error", err, "table", tableName)
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusInternalServerError)
		json.NewEncoder(w).Encode(map[string]string{
			"status":  "ERROR",
			"message": fmt.Sprintf("Unable to create snapshot report: '%s'", err),
		})
		return
	}

	filename := fmt.Sprintf("%s.xlsx", tableName)
	w.Header().Set("Content-Type", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet")
	w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s\"", filename))
	w.Header().Set("File-Name", filename)
	w.Write(reportData)
}

func (h *Handler) renderSnapshotList(w http.ResponseWriter, r *http.Request, snapshotType string, title string, renderer func([]views.SnapshotEntry) templ.Component) {
	ctx := context.Background()
	if err := report.EnsureSnapshotRegistry(ctx, h.Database); err != nil {
		h.Logger.Error("Failed to ensure snapshot registry", "error", err)
		w.WriteHeader(http.StatusInternalServerError)
		fmt.Fprintf(w, "Unable to list snapshot tables: %s\n", err)
		return
	}
	records, err := report.ListSnapshots(ctx, h.Database, snapshotType)
	if err != nil {
		h.Logger.Error("Failed to list snapshots", "error", err, "snapshot_type", snapshotType)
		w.WriteHeader(http.StatusInternalServerError)
		fmt.Fprintf(w, "Unable to list snapshot tables: %s\n", err)
		return
	}

	entries := make([]views.SnapshotEntry, 0, len(records))
	for _, record := range records {
		label := report.FormatSnapshotLabel(snapshotType, record.SnapshotTime, record.TableName)
		entries = append(entries, views.SnapshotEntry{
			Label: label,
			Link:  "/api/report/snapshot?table=" + url.QueryEscape(record.TableName),
			Count: record.SnapshotCount,
		})
	}

	if err := renderer(entries).Render(r.Context(), w); err != nil {
		h.Logger.Error("Failed to render snapshot list", "error", err, "title", title)
		w.WriteHeader(http.StatusInternalServerError)
		fmt.Fprintf(w, "Failed to render snapshot list")
	}
}