// Package config defines Captioneer's command-line configuration.
package config

import (
	"errors"
	"flag"
	"strings"
	"time"
)

const (
	DefaultModelsDir            = "models"
	DefaultOverlayFontFamily    = "Sans"
	MinimumOverlayFinalLifetime = 3 * time.Second
)

type Mode string

const (
	ModeFixed Mode = "fixed"
	ModeVAD   Mode = "vad"
)

type Settings struct {
	Mode               Mode
	ChunkDuration      time.Duration
	ModelsDir          string
	Threads            int
	PreviewThresholdDB float64
}

func Parse() Settings {
	var settings Settings
	mode := ""
	flag.StringVar(&mode, "mode", "", "caption mode: vad or fixed (required)")
	flag.DurationVar(&settings.ChunkDuration, "chunk-duration", time.Second, "fixed chunk size or VAD preview refresh interval")
	flag.StringVar(&settings.ModelsDir, "models-dir", DefaultModelsDir, "directory containing downloaded Sherpa models")
	flag.IntVar(&settings.Threads, "threads", 2, "CPU threads used by recognition and VAD")
	flag.Float64Var(&settings.PreviewThresholdDB, "preview-threshold-dbfs", -45, "RMS dBFS threshold used to begin VAD previews")
	flag.Parse()
	settings.Mode = Mode(mode)
	return settings
}

type OutputMode string

const (
	OutputTerminal OutputMode = "terminal"
	OutputOverlay  OutputMode = "overlay"
	OutputBoth     OutputMode = "both"
)

type OverlayBackend string

const (
	BackendAuto    OverlayBackend = "auto"
	BackendWayland OverlayBackend = "wayland"
	BackendX11     OverlayBackend = "x11"
)

type OverlaySettings struct {
	Backend      OverlayBackend
	Opacity      float64
	FontSize     int
	FontFamily   string
	BottomMargin int
	MaxWidth     int
	Monitor      string
	FinalTimeout time.Duration
	ClickThrough bool
}

type DesktopSettings struct {
	Settings
	Output  OutputMode
	Overlay OverlaySettings
}

func ParseDesktop() DesktopSettings {
	flags := flag.CommandLine
	var desktop DesktopSettings
	var mode string
	var output string
	var backend string
	flags.StringVar(&mode, "mode", "", "caption mode: vad or fixed (required)")
	flags.DurationVar(&desktop.ChunkDuration, "chunk-duration", time.Second, "fixed chunk size or VAD preview refresh interval")
	flags.StringVar(&desktop.ModelsDir, "models-dir", DefaultModelsDir, "directory containing downloaded Sherpa models")
	flags.IntVar(&desktop.Threads, "threads", 2, "CPU threads used by recognition and VAD")
	flags.Float64Var(&desktop.PreviewThresholdDB, "preview-threshold-dbfs", -45, "RMS dBFS threshold used to begin VAD previews")
	flags.StringVar(&output, "output", "", "caption output: terminal, overlay, or both (required)")
	flags.StringVar(&backend, "overlay-backend", "auto", "display backend: auto, wayland, or x11")
	flags.Float64Var(&desktop.Overlay.Opacity, "overlay-opacity", 0.90, "caption background opacity from 0 to 1")
	flags.IntVar(&desktop.Overlay.FontSize, "overlay-font-size", 28, "caption font size in logical pixels")
	flags.StringVar(&desktop.Overlay.FontFamily, "overlay-font-family", DefaultOverlayFontFamily, "caption font family")
	flags.IntVar(&desktop.Overlay.BottomMargin, "overlay-bottom-margin", 100, "distance from the monitor bottom in logical pixels")
	flags.IntVar(&desktop.Overlay.MaxWidth, "overlay-max-width", 1200, "fixed caption width in logical pixels before the monitor safety cap")
	flags.StringVar(&desktop.Overlay.Monitor, "overlay-monitor", "auto", "monitor selection: auto, numeric index, or connector name")
	flags.DurationVar(&desktop.Overlay.FinalTimeout, "overlay-final-timeout", MinimumOverlayFinalLifetime, "completed-caption lifetime; zero keeps lines until the six-line cap removes them")
	flags.BoolVar(&desktop.Overlay.ClickThrough, "overlay-click-through", true, "pass pointer input through the caption window")
	flag.Parse()
	desktop.Mode = Mode(mode)
	desktop.Output = OutputMode(output)
	desktop.Overlay.Backend = OverlayBackend(backend)
	return desktop
}

func (s Settings) Validate() error {
	if s.Mode != ModeFixed && s.Mode != ModeVAD {
		return errors.New("--mode is required and must be either fixed or vad")
	}
	if s.ChunkDuration <= 0 {
		return errors.New("--chunk-duration must be positive")
	}
	if s.Threads <= 0 {
		return errors.New("--threads must be positive")
	}
	return nil
}

func (s DesktopSettings) Validate() error {
	if err := s.Settings.Validate(); err != nil {
		return err
	}
	if s.Output != OutputTerminal && s.Output != OutputOverlay && s.Output != OutputBoth {
		return errors.New("--output is required and must be terminal, overlay, or both")
	}
	if s.Overlay.Backend != BackendAuto && s.Overlay.Backend != BackendWayland && s.Overlay.Backend != BackendX11 {
		return errors.New("--overlay-backend must be auto, wayland, or x11")
	}
	if s.Overlay.Opacity < 0 || s.Overlay.Opacity > 1 {
		return errors.New("--overlay-opacity must be between 0 and 1")
	}
	if s.Overlay.FontSize <= 0 {
		return errors.New("--overlay-font-size must be positive")
	}
	if strings.TrimSpace(s.Overlay.FontFamily) == "" {
		return errors.New("--overlay-font-family cannot be empty")
	}
	if s.Overlay.BottomMargin < 0 {
		return errors.New("--overlay-bottom-margin cannot be negative")
	}
	if s.Overlay.MaxWidth <= 0 {
		return errors.New("--overlay-max-width must be positive")
	}
	if s.Overlay.FinalTimeout < 0 {
		return errors.New("--overlay-final-timeout cannot be negative")
	}
	if s.Overlay.FinalTimeout > 0 && s.Overlay.FinalTimeout < MinimumOverlayFinalLifetime {
		return errors.New("--overlay-final-timeout must be zero or at least 3s")
	}
	if s.Overlay.Monitor == "" {
		return errors.New("--overlay-monitor cannot be empty")
	}
	return nil
}