// Copyright © SixtyFPS GmbH <info@slint-ui.com>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-commercial

use alloc::boxed::Box;
use core::pin::Pin;

use crate::component::ComponentRef;
use crate::lengths::{LogicalLength, LogicalPoint, LogicalRect, LogicalSize, ScaleFactor};

pub trait Renderer {
    /// Returns the size of the given text in logical pixels.
    /// When set, `max_width` means that one need to wrap the text so it does not go further than that
    fn text_size(
        &self,
        font_request: crate::graphics::FontRequest,
        text: &str,
        max_width: Option<LogicalLength>,
        scale_factor: ScaleFactor,
    ) -> LogicalSize;

    /// Returns the (UTF-8) byte offset in the text property that refers to the character that contributed to
    /// the glyph cluster that's visually nearest to the given coordinate. This is used for hit-testing,
    /// for example when receiving a mouse click into a text field. Then this function returns the "cursor"
    /// position.
    fn text_input_byte_offset_for_position(
        &self,
        text_input: Pin<&crate::items::TextInput>,
        pos: LogicalPoint,
    ) -> usize;

    /// That's the opposite of [`Self::text_input_byte_offset_for_position`]
    /// It takes a (UTF-8) byte offset in the text property, and returns a Rectangle
    /// left to the char. It is one logical pixel wide and ends at the baseline.
    fn text_input_cursor_rect_for_byte_offset(
        &self,
        text_input: Pin<&crate::items::TextInput>,
        byte_offset: usize,
    ) -> LogicalRect;

    /// Clear the caches for the items that are being removed
    fn free_graphics_resources(
        &self,
        _component: ComponentRef,
        _items: &mut dyn Iterator<Item = Pin<crate::items::ItemRef<'_>>>,
    ) {
    }

    /// Mark a given region as dirty regardless whether the items actually are dirty.
    ///
    /// Example: when a PopupWindow disapear, the region under the popup needs to be redrawn
    fn mark_dirty_region(&self, _region: crate::item_rendering::DirtyRegion) {}

    #[cfg(feature = "std")] // FIXME: just because of the Error
    /// This function can be used to register a custom TrueType font with Slint,
    /// for use with the `font-family` property. The provided slice must be a valid TrueType
    /// font.
    fn register_font_from_memory(
        &self,
        _data: &'static [u8],
    ) -> Result<(), Box<dyn std::error::Error>> {
        Err("This renderer does not support registering custom fonts.".into())
    }

    #[cfg(feature = "std")]
    /// This function can be used to register a custom TrueType font with Slint,
    /// for use with the `font-family` property. The provided path must refer to a valid TrueType
    /// font.
    fn register_font_from_path(
        &self,
        _path: &std::path::Path,
    ) -> Result<(), Box<dyn std::error::Error>> {
        Err("This renderer does not support registering custom fonts.".into())
    }

    fn register_bitmap_font(&self, _font_data: &'static crate::graphics::BitmapFont) {
        crate::debug_log!("Internal error: The current renderer cannot load fonts build with the `EmbedForSoftwareRenderer` option. Please use the software Renderer, or disable that option when building your slint files");
    }

    /// This function is called through the public API to register a callback that the backend needs to invoke during
    /// different phases of rendering.
    fn set_rendering_notifier(
        &self,
        _callback: Box<dyn crate::api::RenderingNotifier>,
    ) -> Result<(), crate::api::SetRenderingNotifierError> {
        Err(crate::api::SetRenderingNotifierError::Unsupported)
    }

    fn default_font_size(&self) -> LogicalLength;
}