package handler

import (
	"encoding/csv"
	"fmt"
	"net/http"
	"time"

	"github.com/go-chi/chi/v5"
	"github.com/wotra/wotra/internal/service"
)

// ExportHandler serves /api/export routes.
type ExportHandler struct {
	entrySvc   *service.EntryService
	daySvc     *service.DayService
	weekSvc    *service.WeekService
}

func NewExportHandler(e *service.EntryService, d *service.DayService, w *service.WeekService) *ExportHandler {
	return &ExportHandler{entrySvc: e, daySvc: d, weekSvc: w}
}

func (h *ExportHandler) Routes(r chi.Router) {
	r.Get("/export/entries.csv", h.EntriesCSV)
	r.Get("/export/days.csv", h.DaysCSV)
	r.Get("/export/weeks.csv", h.WeeksCSV)
}

// EntriesCSV GET /api/export/entries.csv?from=YYYY-MM-DD&to=YYYY-MM-DD
func (h *ExportHandler) EntriesCSV(w http.ResponseWriter, r *http.Request) {
	from := r.URL.Query().Get("from")
	to := r.URL.Query().Get("to")
	if from == "" { from = "0000-01-01" }
	if to == "" { to = "9999-12-31" }

	es, err := h.entrySvc.List(r.Context(), from, to)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	w.Header().Set("Content-Type", "text/csv")
	w.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="entries-%s.csv"`, time.Now().Format("20060102")))
	cw := csv.NewWriter(w)
	cw.Write([]string{"id", "day_key", "start_time", "end_time", "duration_ms", "note", "auto_stopped"})
	for _, e := range es {
		endStr := ""
		durStr := "0"
		if e.EndTime != nil {
			endStr = time.UnixMilli(*e.EndTime).UTC().Format(time.RFC3339)
			durStr = fmt.Sprintf("%d", *e.EndTime - e.StartTime)
		}
		cw.Write([]string{
			e.ID,
			e.DayKey,
			time.UnixMilli(e.StartTime).UTC().Format(time.RFC3339),
			endStr,
			durStr,
			e.Note,
			fmt.Sprintf("%v", e.AutoStopped),
		})
	}
	cw.Flush()
}

// DaysCSV GET /api/export/days.csv?from=YYYY-MM-DD&to=YYYY-MM-DD
func (h *ExportHandler) DaysCSV(w http.ResponseWriter, r *http.Request) {
	from := r.URL.Query().Get("from")
	to := r.URL.Query().Get("to")
	if from == "" { from = "0000-01-01" }
	if to == "" { to = "9999-12-31" }

	ds, err := h.daySvc.ListDays(r.Context(), from, to)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	w.Header().Set("Content-Type", "text/csv")
	w.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="days-%s.csv"`, time.Now().Format("20060102")))
	cw := csv.NewWriter(w)
	cw.Write([]string{"day_key", "kind", "worked_ms", "worked_hours"})
	for _, d := range ds {
		workedH := fmt.Sprintf("%.2f", float64(d.WorkedMs)/3_600_000)
		cw.Write([]string{d.DayKey, string(d.Kind), fmt.Sprintf("%d", d.WorkedMs), workedH})
	}
	cw.Flush()
}

// WeeksCSV GET /api/export/weeks.csv
func (h *ExportHandler) WeeksCSV(w http.ResponseWriter, r *http.Request) {
	from := r.URL.Query().Get("from")
	to := r.URL.Query().Get("to")
	if from == "" { from = "0000-W01" }
	if to == "" { to = "9999-W53" }

	ws, err := h.weekSvc.ListWeeks(r.Context(), from, to)
	if err != nil {
		writeError(w, http.StatusInternalServerError, err.Error())
		return
	}

	w.Header().Set("Content-Type", "text/csv")
	w.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="weeks-%s.csv"`, time.Now().Format("20060102")))
	cw := csv.NewWriter(w)
	cw.Write([]string{"week_key", "expected_ms", "worked_ms", "delta_ms", "expected_h", "worked_h", "delta_h"})
	for _, wk := range ws {
		cw.Write([]string{
			wk.WeekKey,
			fmt.Sprintf("%d", wk.ExpectedMs),
			fmt.Sprintf("%d", wk.WorkedMs),
			fmt.Sprintf("%d", wk.DeltaMs),
			fmt.Sprintf("%.2f", float64(wk.ExpectedMs)/3_600_000),
			fmt.Sprintf("%.2f", float64(wk.WorkedMs)/3_600_000),
			fmt.Sprintf("%.2f", float64(wk.DeltaMs)/3_600_000),
		})
	}
	cw.Flush()
}