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use crate::fst_properties::mutable_properties::project_properties;
use crate::fst_properties::FstProperties;
use crate::fst_traits::MutableFst;
use crate::semirings::Semiring;

#[derive(Debug, Clone, PartialEq, PartialOrd, Copy)]
/// Different types of labels projection in a FST.
pub enum ProjectType {
    /// Input projection : output labels are replaced with input ones.
    ProjectInput,
    /// Output projection : input labels are replaced with output ones.
    ProjectOutput,
}

/// This operation projects an FST onto its domain or range by either copying
/// each transition input label to its output label or vice versa.
/// # Example 1
///
/// ## Project input
/// ```
/// # #[macro_use] extern crate rustfst;
/// # use anyhow::Result;
/// # use rustfst::utils::{acceptor, transducer};
/// # use rustfst::semirings::{Semiring, IntegerWeight};
/// # use rustfst::fst_impls::VectorFst;
/// # use rustfst::algorithms::{project, ProjectType};
/// # fn main() -> Result<()> {
/// let mut fst : VectorFst<IntegerWeight> = fst![2 => 3];
/// project(&mut fst, ProjectType::ProjectInput);
/// assert_eq!(fst, fst![2]);
/// # Ok(())
/// # }
/// ```
///
/// ## Project output
///
/// ```rust
/// # #[macro_use] extern crate rustfst;
/// # use anyhow::Result;
/// # use rustfst::utils::{acceptor, transducer};
/// # use rustfst::semirings::{Semiring, IntegerWeight};
/// # use rustfst::fst_impls::VectorFst;
/// # use rustfst::algorithms::{project, ProjectType};
/// # fn main() -> Result<()> {
/// let mut fst : VectorFst<IntegerWeight> = fst![2 => 3];
/// project(&mut fst, ProjectType::ProjectOutput);
/// assert_eq!(fst, fst![3]);
/// # Ok(())
/// # }
/// ```
///
/// # Example 2
///
/// ## Input
///
/// ![project_in](https://raw.githubusercontent.com/Garvys/rustfst-images-doc/master/images/project_in.svg?sanitize=true)
///
/// ## Project input
///
/// ![project_out_project-input](https://raw.githubusercontent.com/Garvys/rustfst-images-doc/master/images/project_out_project-input.svg?sanitize=true)
///
/// ## Project output
///
/// ![project_out_project-input](https://raw.githubusercontent.com/Garvys/rustfst-images-doc/master/images/project_out_project-output.svg?sanitize=true)
pub fn project<W: Semiring, F: MutableFst<W>>(fst: &mut F, project_type: ProjectType) {
    let props = fst.properties();
    match project_type {
        ProjectType::ProjectInput => {
            for state in fst.states_range() {
                let mut it_trs = unsafe { fst.tr_iter_unchecked_mut(state) };
                for idx_tr in 0..it_trs.len() {
                    let tr = unsafe { it_trs.get_unchecked(idx_tr) };
                    let ilabel = tr.ilabel;
                    unsafe { it_trs.set_olabel_unchecked(idx_tr, ilabel) }
                }
            }
        }
        ProjectType::ProjectOutput => {
            for state in fst.states_range() {
                let mut it_trs = unsafe { fst.tr_iter_unchecked_mut(state) };
                for idx_tr in 0..it_trs.len() {
                    let tr = unsafe { it_trs.get_unchecked(idx_tr) };
                    let olabel = tr.olabel;
                    unsafe { it_trs.set_ilabel_unchecked(idx_tr, olabel) }
                }
            }
        }
    };
    fst.set_properties_with_mask(
        project_properties(props, project_type),
        FstProperties::all_properties(),
    );
}

#[cfg(test)]
mod tests {
    use proptest::prelude::*;

    use crate::fst_properties::FstProperties;
    use crate::fst_traits::CoreFst;
    use crate::prelude::*;

    use super::*;

    proptest! {
        #[test]
        fn test_project_input_proptest(mut fst in any::<VectorFst<TropicalWeight>>()) {
            project(&mut fst, ProjectType::ProjectInput);
            prop_assert!(fst.properties().intersects(FstProperties::ACCEPTOR));
        }
    }

    proptest! {
        #[test]
        fn test_project_output_proptest(mut fst in any::<VectorFst<TropicalWeight>>()) {
            project(&mut fst, ProjectType::ProjectOutput);
            prop_assert!(fst.properties().intersects(FstProperties::ACCEPTOR));
        }
    }
}