package app

import (
	"context"
	"fmt"
	"slices"
	"strings"

	"gitea.nik4nao.com/nik/home-services/discord-bot/internal/core/ports/driven"
)

// Choice is one Discord autocomplete entry.
type Choice struct {
	Label string
	Value string
}

// CommandApp orchestrates Discord command use cases against ha-gateway.
type CommandApp struct {
	ha driven.HAGateway
	ai driven.AIGateway
}

// NewCommandApp constructs the Discord command application service.
func NewCommandApp(ha driven.HAGateway, ai driven.AIGateway) *CommandApp {
	return &CommandApp{ha: ha, ai: ai}
}

// HandleLightList formats discovered lights into a monospace-friendly response.
func (a *CommandApp) HandleLightList(ctx context.Context) (string, error) {
	lights, err := a.ha.ListLights(ctx)
	if err != nil {
		return "", fmt.Errorf("handle light list: %w", err)
	}
	if len(lights) == 0 {
		return "No lights found.", nil
	}

	lines := make([]string, 0, len(lights)+2)
	lines = append(lines, "```text")
	for _, light := range lights {
		lines = append(lines, formatLightLine(light))
	}
	lines = append(lines, "```")
	return strings.Join(lines, "\n"), nil
}

// HandleLightOn issues a turn-on request and returns a user-facing confirmation.
func (a *CommandApp) HandleLightOn(ctx context.Context, entityID string, brightnessPct *uint32, colorTempKelvin *uint32) (string, error) {
	name, err := a.lookupLightName(ctx, entityID)
	if err != nil {
		return "", fmt.Errorf("lookup light name: %w", err)
	}
	if err := a.ha.TurnOnLight(ctx, entityID, brightnessPct, colorTempKelvin); err != nil {
		return "", fmt.Errorf("handle light on: %w", err)
	}

	details := make([]string, 0, 2)
	if brightnessPct != nil {
		details = append(details, fmt.Sprintf("brightness %d%%", *brightnessPct))
	}
	if colorTempKelvin != nil {
		details = append(details, fmt.Sprintf("%dK", *colorTempKelvin))
	}
	if len(details) == 0 {
		return fmt.Sprintf("Turned on `%s`.", name), nil
	}
	return fmt.Sprintf("Turned on `%s` (%s).", name, strings.Join(details, ", ")), nil
}

// HandleLightOff issues a turn-off request and returns a user-facing confirmation.
func (a *CommandApp) HandleLightOff(ctx context.Context, entityID string, transition *uint32) (string, error) {
	name, err := a.lookupLightName(ctx, entityID)
	if err != nil {
		return "", fmt.Errorf("lookup light name: %w", err)
	}
	if err := a.ha.TurnOffLight(ctx, entityID, transition); err != nil {
		return "", fmt.Errorf("handle light off: %w", err)
	}
	if transition == nil {
		return fmt.Sprintf("Turned off `%s`.", name), nil
	}
	return fmt.Sprintf("Turned off `%s` with %ds transition.", name, *transition), nil
}

// HandleLightToggle issues a toggle request and returns a user-facing confirmation.
func (a *CommandApp) HandleLightToggle(ctx context.Context, entityID string) (string, error) {
	name, err := a.lookupLightName(ctx, entityID)
	if err != nil {
		return "", fmt.Errorf("lookup light name: %w", err)
	}
	if err := a.ha.ToggleLight(ctx, entityID); err != nil {
		return "", fmt.Errorf("handle light toggle: %w", err)
	}
	return fmt.Sprintf("Toggled `%s`.", name), nil
}

// HandleSwitchList formats discovered switches into a monospace-friendly response.
func (a *CommandApp) HandleSwitchList(ctx context.Context) (string, error) {
	switches, err := a.ha.ListSwitches(ctx)
	if err != nil {
		return "", fmt.Errorf("handle switch list: %w", err)
	}
	if len(switches) == 0 {
		return "No switches found.", nil
	}

	lines := make([]string, 0, len(switches)+2)
	lines = append(lines, "```text")
	for _, sw := range switches {
		label := sw.FriendlyName
		if label == "" {
			label = sw.EntityID
		}
		details := sw.DeviceClass
		if details == "" {
			details = "switch"
		}
		lines = append(lines, fmt.Sprintf("%s %-15s %-12s %s", stateEmoji(sw.State), label, sw.State, details))
	}
	lines = append(lines, "```")
	return strings.Join(lines, "\n"), nil
}

// HandleAIQuery forwards a free-form request to ai-gateway.
func (a *CommandApp) HandleAIQuery(ctx context.Context, text string) (string, error) {
	reply, err := a.ai.Query(ctx, text)
	if err != nil {
		return "", fmt.Errorf("handle ai query: %w", err)
	}
	return reply, nil
}

// AutocompleteLights maps discovered lights into Discord autocomplete choices.
func (a *CommandApp) AutocompleteLights(ctx context.Context) ([]Choice, error) {
	lights, err := a.ha.ListLights(ctx)
	if err != nil {
		return nil, fmt.Errorf("autocomplete lights: %w", err)
	}

	choices := make([]Choice, 0, len(lights))
	for _, light := range lights {
		label := light.FriendlyName
		if label == "" {
			label = light.EntityID
		}
		choices = append(choices, Choice{Label: label, Value: light.EntityID})
	}
	return choices, nil
}

// AutocompleteSwitches maps discovered switches into Discord autocomplete choices.
func (a *CommandApp) AutocompleteSwitches(ctx context.Context) ([]Choice, error) {
	switches, err := a.ha.ListSwitches(ctx)
	if err != nil {
		return nil, fmt.Errorf("autocomplete switches: %w", err)
	}

	choices := make([]Choice, 0, len(switches))
	for _, sw := range switches {
		label := sw.FriendlyName
		if label == "" {
			label = sw.EntityID
		}
		choices = append(choices, Choice{Label: label, Value: sw.EntityID})
	}
	return choices, nil
}

// lookupLightName falls back to the entity ID so confirmations remain useful
// even when Home Assistant does not expose a friendly name.
func (a *CommandApp) lookupLightName(ctx context.Context, entityID string) (string, error) {
	lights, err := a.ha.ListLights(ctx)
	if err != nil {
		return "", fmt.Errorf("list lights: %w", err)
	}
	idx := slices.IndexFunc(lights, func(light driven.Light) bool {
		return light.EntityID == entityID
	})
	if idx == -1 {
		return entityID, nil
	}
	if lights[idx].FriendlyName == "" {
		return entityID, nil
	}
	return lights[idx].FriendlyName, nil
}

// formatLightLine keeps list output compact because Discord code blocks are
// easier to scan than rich embeds for dense discovery data.
func formatLightLine(light driven.Light) string {
	label := light.FriendlyName
	if label == "" {
		label = light.EntityID
	}

	parts := make([]string, 0, 3)
	if len(light.SupportedColorModes) > 0 {
		parts = append(parts, strings.Join(light.SupportedColorModes, ","))
	}
	if light.MinColorTempKelvin > 0 && light.MaxColorTempKelvin > 0 {
		parts = append(parts, fmt.Sprintf("%d-%dK", light.MinColorTempKelvin, light.MaxColorTempKelvin))
	}
	if light.IsHueGroup {
		parts = append(parts, "hue-group")
	}
	details := strings.Join(parts, " ")
	if details == "" {
		details = "-"
	}

	return fmt.Sprintf("%s %-15s %-12s %s", stateEmoji(light.State), label, light.State, details)
}

// stateEmoji compresses common Home Assistant states into visually scannable output.
func stateEmoji(state string) string {
	switch state {
	case "on":
		return "🟢"
	case "off":
		return "🔴"
	default:
		return "⚠️"
	}
}