package httpapi

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

	"github.com/vasyansk/imap-copier/internal/scheduler"
	"github.com/vasyansk/imap-copier/internal/store"
)

func (s *Server) handleCreateTask(w http.ResponseWriter, r *http.Request) {
	var t store.Task
	if err := json.NewDecoder(r.Body).Decode(&t); err != nil {
		http.Error(w, "bad json", http.StatusBadRequest)
		return
	}
	id, err := s.store.CreateTask(r.Context(), t)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	writeJSON(w, http.StatusCreated, map[string]int64{"id": id})
}

func (s *Server) handleListTasks(w http.ResponseWriter, r *http.Request) {
	tasks, err := s.store.ListTasks(r.Context())
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	writeJSON(w, http.StatusOK, tasks)
}

func (s *Server) handleGetTask(w http.ResponseWriter, r *http.Request) {
	id, err := pathID(r, "id")
	if err != nil {
		http.Error(w, "bad id", http.StatusBadRequest)
		return
	}
	task, err := s.store.GetTask(r.Context(), id)
	if err != nil {
		http.Error(w, "not found", http.StatusNotFound)
		return
	}
	accs, err := s.store.ListAccountsByTask(r.Context(), id)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	views := make([]AccountView, 0, len(accs))
	for _, a := range accs {
		views = append(views, accountDTO(a))
	}
	writeJSON(w, http.StatusOK, map[string]any{"task": s.taskViewFor(r.Context(), task), "accounts": views})
}

// taskView augments the stored task with the server-computed next scheduled run
// (RFC3339 UTC; null when the schedule is off, the task is running, or broken).
type taskView struct {
	store.Task
	NextRunAt *string `json:"next_run_at"`
}

func (s *Server) taskViewFor(ctx context.Context, t store.Task) taskView {
	var nextRunAt *string
	if t.ScheduleIntervalSeconds > 0 && !t.Broken && t.Status != "running" && t.ScheduleAnchor != nil {
		last, _ := s.store.LastFinishedRunAt(ctx, t.ID)
		n := scheduler.NextRun(time.Duration(t.ScheduleIntervalSeconds)*time.Second, *t.ScheduleAnchor, last)
		str := n.UTC().Format(time.RFC3339)
		nextRunAt = &str
	}
	return taskView{Task: t, NextRunAt: nextRunAt}
}

// handleSetSchedule enables/changes/disables a task's recurring schedule.
// Enabling (interval>0) requires every account to pass its connection tests.
func (s *Server) handleSetSchedule(w http.ResponseWriter, r *http.Request) {
	taskID, err := pathID(r, "id")
	if err != nil {
		http.Error(w, "bad id", http.StatusBadRequest)
		return
	}
	var body struct {
		IntervalSeconds int64 `json:"interval_seconds"`
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		http.Error(w, "bad json", http.StatusBadRequest)
		return
	}
	if body.IntervalSeconds > 0 {
		accs, err := s.store.ListAccountsByTask(r.Context(), taskID)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		if !allAccountsTested(accs) {
			http.Error(w, "all accounts must pass connection tests before scheduling", http.StatusConflict)
			return
		}
	}
	if err := s.store.SetTaskSchedule(r.Context(), taskID, body.IntervalSeconds); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	w.WriteHeader(http.StatusNoContent)
}

// allAccountsTested mirrors the orchestrator's run gate: non-empty and every
// account OK on both sides.
func allAccountsTested(accs []store.Account) bool {
	if len(accs) == 0 {
		return false
	}
	for _, a := range accs {
		if a.TestSrcStatus != "ok" || a.TestDstStatus != "ok" {
			return false
		}
	}
	return true
}

func (s *Server) handleListRuns(w http.ResponseWriter, r *http.Request) {
	taskID, err := pathID(r, "id")
	if err != nil {
		http.Error(w, "bad id", http.StatusBadRequest)
		return
	}
	runs, err := s.store.ListRunsByTask(r.Context(), taskID)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	writeJSON(w, http.StatusOK, runs)
}