package chat

import (
	"encoding/json"
	"log/slog"
	"os"
	"strings"

	"github.com/ayn2op/discordo/internal/config"
	"github.com/ayn2op/discordo/internal/ui"
	"github.com/ayn2op/tview"
	"github.com/ayn2op/tview/keybind"
	"github.com/ayn2op/tview/list"
	"github.com/ayn2op/tview/picker"
	"github.com/gdamore/tcell/v3"
)

func ConfigurePicker(model *picker.Model, cfg *config.Config, title string) {
	model.Box = ui.ConfigureBox(tview.NewBox(), &cfg.Theme)
	// When a child of the parent flex is focused, the parent layout itself is not reported as focused.
	// Instead, the focused child (picker) is considered focused.
	// Therefore, we manually set the active border style on the picker to ensure it displays the correct focused appearance.
	model.
		SetBlurFunc(nil).
		SetFocusFunc(nil).
		SetBorderSet(cfg.Theme.Border.ActiveSet.BorderSet).
		SetBorderStyle(cfg.Theme.Border.ActiveStyle.Style).
		SetTitleStyle(cfg.Theme.Title.ActiveStyle.Style).
		SetFooterStyle(cfg.Theme.Footer.ActiveStyle.Style)

	model.SetTitle(title)
	model.SetScrollBarVisibility(cfg.Theme.ScrollBar.Visibility.ScrollBarVisibility)
	model.SetScrollBar(tview.NewScrollBar().
		SetTrackStyle(cfg.Theme.ScrollBar.TrackStyle.Style).
		SetThumbStyle(cfg.Theme.ScrollBar.ThumbStyle.Style).
		SetGlyphSet(cfg.Theme.ScrollBar.GlyphSet.GlyphSet))
	model.SetKeybinds(picker.Keybinds{
		Cancel: cfg.Keybinds.Picker.Cancel.Keybind,
		Keybinds: list.Keybinds{
			SelectUp:     cfg.Keybinds.Picker.Up.Keybind,
			SelectDown:   cfg.Keybinds.Picker.Down.Keybind,
			SelectTop:    cfg.Keybinds.Picker.Top.Keybind,
			SelectBottom: cfg.Keybinds.Picker.Bottom.Keybind,
		},
		Select: cfg.Keybinds.Picker.Select.Keybind,
	})
}

// browseKeyHandler is an optional callback for picker-specific keys in browse
// mode. Return (cmd, true) if handled, (nil, false) to fall through.
type browseKeyHandler func(event *tview.KeyEvent) (tview.Command, bool)

// pickerBrowseHandleKey implements a two-phase ESC for overlay pickers.
// First ESC enters browse mode (j/k navigate, i returns to input).
// Second ESC calls closeFn to close the picker.
// Returns (command, handled). If handled is false, the caller should
// fall through to the normal picker event handling.
// The optional extra handlers are checked before the default swallow-all,
// allowing pickers to add custom browse-mode keys (e.g. favorite toggle).
func pickerBrowseHandleKey(event *tview.KeyEvent, browseMode *bool, model *picker.Model, closeFn func(), extra ...browseKeyHandler) (tview.Command, bool) {
	if !*browseMode {
		if event.Key() == tcell.KeyEsc {
			*browseMode = true
			return nil, true
		}
		return nil, false
	}

	// Browse mode: intercept keys before they reach the input field.
	switch {
	case event.Key() == tcell.KeyEsc:
		*browseMode = false
		closeFn()
		return nil, true
	case event.Key() == tcell.KeyRune && event.Str() == "i":
		*browseMode = false
		return nil, true
	case event.Key() == tcell.KeyRune && event.Str() == "j":
		return model.HandleEvent(tcell.NewEventKey(tcell.KeyCtrlN, "", tcell.ModCtrl)), true
	case event.Key() == tcell.KeyRune && event.Str() == "k":
		return model.HandleEvent(tcell.NewEventKey(tcell.KeyCtrlP, "", tcell.ModCtrl)), true
	case event.Key() == tcell.KeyRune && event.Str() == "g":
		return model.HandleEvent(tcell.NewEventKey(tcell.KeyHome, "", tcell.ModNone)), true
	case event.Key() == tcell.KeyRune && event.Str() == "G":
		return model.HandleEvent(tcell.NewEventKey(tcell.KeyEnd, "", tcell.ModNone)), true
	case event.Key() == tcell.KeyEnter:
		return model.HandleEvent(event), true
	}

	// Check extra handlers before swallowing.
	for _, handler := range extra {
		if cmd, handled := handler(event); handled {
			return cmd, true
		}
	}

	// Swallow other keys in browse mode so they don't reach the input.
	return nil, true
}

// pickerShortHelp returns the standard short help for any picker overlay.
func pickerShortHelp(cfg config.PickerKeybinds) []keybind.Keybind {
	return []keybind.Keybind{cfg.Up.Keybind, cfg.Down.Keybind, cfg.Select.Keybind, cfg.Cancel.Keybind}
}

// pickerFullHelp returns the standard full help for any picker overlay.
func pickerFullHelp(cfg config.PickerKeybinds) [][]keybind.Keybind {
	return [][]keybind.Keybind{
		{cfg.Up.Keybind, cfg.Down.Keybind, cfg.Top.Keybind, cfg.Bottom.Keybind},
		{cfg.Select.Keybind, cfg.Cancel.Keybind},
	}
}

// atomicSaveJSON marshals v as JSON and atomically writes it to path
// via a tmp+rename pattern with 0600 permissions.
func atomicSaveJSON(path string, v any) {
	data, err := json.Marshal(v)
	if err != nil {
		slog.Error("failed to marshal JSON", "path", path, "err", err)
		return
	}
	tmpPath := path + ".tmp"
	if err := os.WriteFile(tmpPath, data, 0600); err != nil {
		slog.Error("failed to write JSON", "path", path, "err", err)
		return
	}
	if err := os.Rename(tmpPath, path); err != nil {
		slog.Error("failed to rename JSON file", "path", path, "err", err)
	}
}

func humanJoin(items []string) string {
	count := len(items)
	switch count {
	case 0:
		return ""
	case 1:
		return items[0]
	case 2:
		return items[0] + " and " + items[1]
	default:
		return strings.Join(items[:count-1], ", ") + ", and " + items[count-1]
	}
}