package agents

import (
	"context"
	"fmt"
	"log/slog"
	"slices"
	"strings"
	"time"

	"g.fc.run/misc/byre/internal/api"
	"g.fc.run/misc/byre/internal/store"
)

func (m *Manager) Respond(ctx context.Context, user string, creates []api.InboxResponseCreate) ([]api.InboxItem, error) {
	if len(creates) == 0 {
		return nil, fmt.Errorf("%w: responses is empty", ErrInvalid)
	}

	resolutions := []store.Resolution{}
	sessions := []string{}
	seen := map[string]bool{}

	for _, create := range creates {
		if seen[create.ItemId] {
			return nil, fmt.Errorf("%w: item %s answered twice in one submission", ErrInvalid, create.ItemId)
		}
		seen[create.ItemId] = true

		item, err := m.store.GetInboxItem(ctx, create.ItemId)
		if err != nil {
			return nil, err
		}

		state, err := CheckResponse(item, create)
		if err != nil {
			return nil, err
		}

		attachments := []api.Attachment{}
		if create.Attachments != nil {
			attachments = *create.Attachments
		}

		resolutions = append(resolutions, store.Resolution{
			State: state,
			Response: api.InboxResponse{
				Id:          store.NewID(),
				ItemId:      item.Id,
				User:        user,
				Type:        create.Type,
				Options:     create.Options,
				Text:        create.Text,
				Attachments: attachments,
				CreatedAt:   time.Now().UTC(),
			},
		})
		if !slices.Contains(sessions, item.AgentSessionId) {
			sessions = append(sessions, item.AgentSessionId)
		}
	}

	err := m.store.Respond(ctx, user, resolutions)
	if err != nil {
		slog.Error("record inbox responses", "user", user, "err", err)
		return nil, err
	}
	for _, res := range resolutions {
		slog.Info("inbox response recorded", "item", res.Response.ItemId, "response", res.Response.Id, "type", res.Response.Type, "user", user)
	}

	for _, id := range sessions {
		go func() {
			err := m.Deliver(context.Background(), id)
			if err != nil {
				slog.Error("deliver inbox responses", "session", id, "err", err)
			}
		}()
	}

	items := []api.InboxItem{}
	for _, res := range resolutions {
		item, err := m.store.GetInboxItem(ctx, res.Response.ItemId)
		if err != nil {
			return nil, err
		}
		items = append(items, item)
	}
	return items, nil
}

func CheckResponse(item api.InboxItem, c api.InboxResponseCreate) (api.InboxState, error) {
	if item.State != api.Open {
		return "", fmt.Errorf("%w: item %s is %s", ErrConflict, item.Id, item.State)
	}

	text := ""
	if c.Text != nil {
		text = strings.TrimSpace(*c.Text)
	}
	question := item.Kind == api.Question
	bad := func(format string, args ...any) (api.InboxState, error) {
		return "", fmt.Errorf("%w: item %s: "+format, append([]any{ErrInvalid, item.Id}, args...)...)
	}

	switch c.Type {
	case api.Option:
		if !question {
			return bad("only questions have options")
		}
		if c.Options == nil || len(*c.Options) == 0 {
			return bad("option needs the chosen options")
		}
		if item.Payload["multiple"] != true && len(*c.Options) != 1 {
			return bad("a pick-one question takes exactly one option")
		}
		seen := map[string]bool{}
		for _, o := range *c.Options {
			if !hasOption(item, o) {
				return bad("%q is not one of the question's options", o)
			}
			if seen[o] {
				return bad("%q chosen twice", o)
			}
			seen[o] = true
		}
		if text != "" && item.Payload["multiple"] != true {
			return bad("a pick-one option takes no text; use other")
		}
		return api.Answered, nil

	case api.Other:
		if text == "" {
			return bad("other needs text")
		}
		return api.Answered, nil

	case api.Dismiss:
		if question {
			return bad("questions need an option or other, not a dismissal")
		}
		return api.Dismissed, nil
	}

	return bad("unknown response type %q", c.Type)
}

func hasOption(item api.InboxItem, option string) bool {
	options, ok := item.Payload["options"].([]any)
	if !ok {
		return false
	}
	for _, o := range options {
		if o == option {
			return true
		}
	}
	return false
}