#![deny(missing_docs)]

//! Access glyphs outlines. Requires the `outline` cargo feature (enabled by default).

//!

//! This module is used to access the outlines of glyphs as a series of foundational drawing

//! instruction callbacks on implementors of the `OutlineSink` trait. Outlines from `glyf` and

//! `CFF` tables can be accessed.

//!

//! ### Example

//!

//! This is a fairly complete example of mapping some glyphs and then visiting their outlines with

//! support for TrueType and CFF fonts. It accumulates the drawing operations into a `String`.

//! In a real application you'd probably make calls to a graphics library instead.

//!

//! ```

//! use std::fmt::Write;

//!

//! use allsorts::binary::read::ReadScope;

//! use allsorts::cff::outline::CFFOutlines;

//! use allsorts::cff::CFF;

//! use allsorts::font::{GlyphTableFlag, MatchingPresentation};

//! use allsorts::font_data::FontData;

//! use allsorts::gsub::RawGlyph;

//! use allsorts::outline::{OutlineBuilder, OutlineSink};

//! use allsorts::pathfinder_geometry::line_segment::LineSegment2F;

//! use allsorts::pathfinder_geometry::vector::Vector2F;

//! use allsorts::tables::glyf::{GlyfVisitorContext, LocaGlyf};

//! use allsorts::tables::loca::{owned, LocaTable};

//! use allsorts::tables::{FontTableProvider, SfntVersion};

//! use allsorts::{tag, Font};

//!

//! struct DebugVisitor {

//!     outlines: String,

//! }

//!

//! impl OutlineSink for DebugVisitor {

//!     fn move_to(&mut self, to: Vector2F) {

//!         writeln!(&mut self.outlines, "move_to({}, {})", to.x(), to.y()).unwrap();

//!     }

//!

//!     fn line_to(&mut self, to: Vector2F) {

//!         writeln!(&mut self.outlines, "line_to({}, {})", to.x(), to.y()).unwrap();

//!     }

//!

//!     fn quadratic_curve_to(&mut self, control: Vector2F, to: Vector2F) {

//!         writeln!(

//!             &mut self.outlines,

//!             "quad_to({}, {}, {}, {})",

//!             control.x(),

//!             control.y(),

//!             to.x(),

//!             to.y()

//!         )

//!         .unwrap();

//!     }

//!

//!     fn cubic_curve_to(&mut self, control: LineSegment2F, to: Vector2F) {

//!         writeln!(

//!             &mut self.outlines,

//!             "curve_to({}, {}, {}, {}, {}, {})",

//!             control.from_x(),

//!             control.from_y(),

//!             control.to_x(),

//!             control.to_y(),

//!             to.x(),

//!             to.y()

//!         )

//!         .unwrap();

//!     }

//!

//!     fn close(&mut self) {

//!         writeln!(&mut self.outlines, "close()").unwrap();

//!     }

//! }

//!

//! fn main() -> Result<(), Box<dyn std::error::Error>> {

//!     let script = tag::LATN;

//!     let buffer = std::fs::read("tests/fonts/opentype/Klei.otf")?;

//!     let scope = ReadScope::new(&buffer);

//!     let font_file = scope.read::<FontData<'_>>()?;

//!     let provider = font_file.table_provider(0)?;

//!     let mut font = Font::new(provider)?;

//!     let mut sink = DebugVisitor {

//!         outlines: String::new(),

//!     };

//!

//!     // Map text to glyphs

//!     let glyphs = font.map_glyphs("+", script, MatchingPresentation::NotRequired);

//!

//!     // Visit the outlines of each glyph. Read tables depending on the type of font

//!     if font.glyph_table_flags.contains(GlyphTableFlag::CFF)

//!         && font.font_table_provider.sfnt_version() == tag::OTTO

//!     {

//!         let cff_data = font.font_table_provider.read_table_data(tag::CFF)?;

//!         let cff = ReadScope::new(&cff_data).read::<CFF<'_>>()?;

//!         let mut cff_outlines = CFFOutlines { table: &cff };

//!         sink.glyphs_to_path(&mut cff_outlines, &glyphs)?;

//!     } else if font.glyph_table_flags.contains(GlyphTableFlag::GLYF) {

//!         let loca_data = font.font_table_provider.read_table_data(tag::LOCA)?;

//!         let loca = ReadScope::new(&loca_data).read_dep::<LocaTable<'_>>((

//!             font.maxp_table.num_glyphs,

//!             font.head_table.index_to_loc_format,

//!         ))?;

//!         let glyf_data = font

//!             .font_table_provider

//!             .read_table_data(tag::GLYF)

//!             .map(Box::from)?;

//!         let mut loca_glyf = LocaGlyf::loaded(owned::LocaTable::from(&loca), glyf_data);

//!         let mut ctx = GlyfVisitorContext::new(&mut loca_glyf, None);

//!         sink.glyphs_to_path(&mut ctx, &glyphs)?;

//!     } else {

//!         return Err("no glyf or CFF table".into());

//!     }

//!

//!     let expected = "move_to(225, 152)

//! line_to(225, 269)

//! curve_to(225, 274, 228, 276, 232, 276)

//! line_to(341, 276)

//! curve_to(346, 276, 347, 285, 347, 295)

//! curve_to(347, 307, 345, 320, 341, 320)

//! line_to(232, 320)

//! curve_to(226, 320, 226, 325, 226, 328)

//! line_to(226, 432)

//! curve_to(220, 435, 214, 437, 206, 437)

//! curve_to(198, 437, 190, 435, 181, 432)

//! line_to(181, 329)

//! curve_to(181, 326, 180, 320, 172, 320)

//! line_to(68, 320)

//! curve_to(62, 320, 59, 311, 59, 300)

//! curve_to(59, 289, 62, 278, 68, 276)

//! line_to(174, 276)

//! curve_to(179, 276, 181, 271, 181, 267)

//! line_to(181, 152)

//! curve_to(181, 147, 193, 144, 204, 144)

//! curve_to(215, 144, 225, 147, 225, 152)

//! close()

//! ";

//!     assert_eq!(sink.outlines, expected);

//!     Ok(())

//! }

//!

//! impl DebugVisitor {

//!     pub fn glyphs_to_path<T>(

//!         &mut self,

//!         builder: &mut T,

//!         glyphs: &[RawGlyph<()>],

//!     ) -> Result<(), Box<dyn std::error::Error>>

//!     where

//!         T: OutlineBuilder,

//!         <T as OutlineBuilder>::Error: 'static,

//!     {

//!         for glyph in glyphs {

//!             builder.visit(glyph.glyph_index, None, self)?;

//!         }

//!

//!         Ok(())

//!     }

//! }

//! ```

use std::cmp::Ordering;

use pathfinder_geometry::vector::Vector2F;

use pathfinder_geometry::{line_segment::LineSegment2F, rect::RectF};

use tinyvec::{array_vec, ArrayVec};

use crate::tables::glyf::{BoundingBox, Point as GlyfPoint};

use crate::tables::variable_fonts::OwnedTuple;

use crate::TryNumFrom;

#[derive(Clone, Copy, Debug)]

pub(crate) struct BBox {

    rect: Option<RectF>,

}

/// Trait for visiting a glyph outline and delivering drawing commands to an `OutlineSink`.

pub trait OutlineBuilder {

    /// The error type returned by the `visit` method.

    type Error: std::error::Error;

    /// The output type returned by the `visit` method.

    type Output;

    /// Visit the glyph outlines in `self`.

    fn visit<S: OutlineSink>(

        &mut self,

        glyph_index: u16,

        tuple: Option<&OwnedTuple>,

        sink: &mut S,

    ) -> Result<Self::Output, Self::Error>;

}

// `OutlineSink` is from font-kit, font-kit/src/outline.rs:

//

// Copyright © 2020 The Pathfinder Project Developers.

//

// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or

// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license

// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your

// option. This file may not be copied, modified, or distributed

// except according to those terms.

/// A trait for visiting a glyph outline

pub trait OutlineSink {

    /// Moves the pen to a point.

    fn move_to(&mut self, to: Vector2F);

    /// Draws a line to a point.

    fn line_to(&mut self, to: Vector2F);

    /// Draws a quadratic Bézier curve to a point.

    fn quadratic_curve_to(&mut self, ctrl: Vector2F, to: Vector2F);

    /// Draws a cubic Bézier curve to a point.

    fn cubic_curve_to(&mut self, ctrl: LineSegment2F, to: Vector2F);

    /// Closes the path, returning to the first point in it.

    fn close(&mut self);

}

/// An [OutlineSink] that computes the bounding box of a glyph.

pub struct BoundingBoxSink {

    prev_point: Vector2F,

    bbox: BBox,

}

impl BBox {

        // Extend the existing rect or initialise it with an empty rect containing

        // only `point`.

            }),

        }

}

impl BoundingBoxSink {

    /// Construct a new `BoundingBoxSink` for use with [OutlineBuilder].

    /// Returns the calculated bounding box of the glyph outline.

}

impl OutlineSink for BoundingBoxSink {

        // https://iquilezles.org/articles/bezierbbox/

        // If the box around the start point and end point contains the control point,

        // then that is the bounding box of the curve. Otherwise we need to find the

        // extrema of the curve.

            // Calculate where derivative is zero

        // If the box around the start point and end point contains both control points,

        // then that is the bounding box of the curve. Otherwise we need to find the

        // extrema of the curve.

        // Nothing to do. Close returns the starting point, which is already contained in the bbox.

}

// References:

//

// The Math Behind Bezier Cubic Splines

// http://www.tinaja.com/glib/cubemath.pdf

//

// Warping Text To Bézier curves

// http://www.planetclegg.com/projects/WarpingTextToSplines.html

/// A-H values in equation space

#[derive(Debug, Copy, Clone)]

struct BezierCoefficients {

    pub ae: Vector2F,

    pub bf: Vector2F,

    pub cg: Vector2F,

    pub dh: Vector2F,

}

impl BezierCoefficients {

    #[cfg(test)]

    fn as_array(&self) -> [f32; 8] {

        [

            self.ae.x(),

            self.bf.x(),

            self.cg.x(),

            self.dh.x(),

            self.ae.y(),

            self.bf.y(),

            self.cg.y(),

            self.dh.y(),

        ]

    }

}

// Finding extremities: root finding

// https://pomax.github.io/bezierinfo/#extremities

        //  𝑓ʹ(𝑡) = 𝑎𝑡² + 𝑏𝑡 + 𝑐

        //      0 = 𝑏𝑡 + 𝑐

        //      𝑡 = -𝑐/𝑏

        } else {

            // If B is some very small value but not quite zero, T can end up as

            // a very large value risking overflow. Address if needed.

        }

    } else {

    };

// https://en.wikipedia.org/wiki/Quadratic_formula

// https://apps.dtic.mil/sti/tr/pdf/AD0639052.pdf

// https://s3.amazonaws.com/nrbook.com/book_C210_pdf/chap10c.pdf

// 𝑎𝑥² + 𝑏𝑥 + 𝑐 = 0

    // The quantity Δ = b² − 4ac is known as the discriminant of the quadratic equation.

        // when Δ < 0, the equation has no real roots

        // when Δ = 0, the equation has one repeated real root

        // when Δ > 0, the equation has two distinct real roots

        Ordering::Greater => {

            // Avoid catastrophic cancellation

            // https://en.wikipedia.org/wiki/Quadratic_formula#Numerical_calculation

            // https://people.csail.mit.edu/bkph/articles/Quadratics.pdf

                Ordering::Less => {

                }

                Ordering::Equal => {

                }

                Ordering::Greater => {

                }

            }

        }

    }

impl From<GlyfPoint> for Vector2F {

}

#[cfg(test)]

mod tests {

    use pathfinder_geometry::vector::vec2f;

    use crate::assert_close;

    use super::*;

    // First two test cases from:

    // https://apps.dtic.mil/sti/tr/pdf/AD0639052.pdf §6 p. 10

    #[test]

    fn test_solve_quadratic1() {

        let res = solve_quadratic(6.0, 5.0, -4.0);

        let &[root1, root2] = res.as_slice() else {

            panic!("Expected two roots");

        };

        assert_close!(root1, -1.33333333);

        assert_close!(root2, 0.5);

    }

    #[test]

    fn test_solve_quadratic2() {

        let res = solve_quadratic(1.0, 100000.0, 1.0);

        let &[root1, root2] = res.as_slice() else {

            panic!("Expected two roots");

        };

        assert_close!(root1, -100000.0);

        assert_close!(root2, -0.00001);

    }

    #[test]

    fn bezier_coefficients() {

        let actual = BezierCoefficients::new(

            vec2f(110., 150.),

            vec2f(25., 190.),

            vec2f(210., 250.),

            vec2f(210., 30.),

        );

        let expected = [-455.0_f32, 810.0, -255.0, 110.0, -300.0, 60.0, 120.0, 150.0];

        for (&a, &b) in actual.as_array().iter().zip(expected.iter()) {

            assert_close!(a, b);

        }

    }

    #[test]

    fn quadratic_bbox() {

        let mut sink = BoundingBoxSink::new();

        let start = vec2f(82.148931, 87.063829);

        sink.move_to(start);

        let ctrl = vec2f(91.627661, 5.968085099999996);

        let to = vec2f(103.56383, 64.595743);

        sink.quadratic_curve_to(ctrl, to);

        let bbox = sink.bbox.rect.unwrap();

        assert_close!(bbox.origin_x(), 82.148931);

        assert_close!(bbox.origin_y(), 39.995697);

        assert_close!(bbox.width(), 103.56383 - 82.148931);

        assert_close!(bbox.height(), 87.063829 - 39.995697);

    }

}