use crate::completions::{matches, Completer, CompletionOptions};
use nu_protocol::{
    engine::{EngineState, StateWorkingSet},
    levenshtein_distance, Span,
};
use reedline::Suggestion;
use std::fs;
use std::path::Path;
use std::sync::Arc;

use super::{partial_from, prepend_base_dir, SortBy};

const SEP: char = std::path::MAIN_SEPARATOR;

#[derive(Clone)]
pub struct DirectoryCompletion {
    engine_state: Arc<EngineState>,
}

impl DirectoryCompletion {
    pub fn new(engine_state: Arc<EngineState>) -> Self {
        Self { engine_state }
    }
}

impl Completer for DirectoryCompletion {
    fn fetch(
        &mut self,
        _: &StateWorkingSet,
        prefix: Vec<u8>,
        span: Span,
        offset: usize,
        _: usize,
        options: &CompletionOptions,
    ) -> Vec<Suggestion> {
        let cwd = self.engine_state.current_work_dir();
        let partial = String::from_utf8_lossy(&prefix).to_string();

        // Filter only the folders
        let output: Vec<_> = directory_completion(span, &partial, &cwd, options)
            .into_iter()
            .map(move |x| Suggestion {
                value: x.1,
                description: None,
                extra: None,
                span: reedline::Span {
                    start: x.0.start - offset,
                    end: x.0.end - offset,
                },
                append_whitespace: false,
            })
            .collect();

        output
    }

    // Sort results prioritizing the non hidden folders
    fn sort(&self, items: Vec<Suggestion>, prefix: Vec<u8>) -> Vec<Suggestion> {
        let prefix_str = String::from_utf8_lossy(&prefix).to_string();

        // Sort items
        let mut sorted_items = items;

        match self.get_sort_by() {
            SortBy::Ascending => {
                sorted_items.sort_by(|a, b| a.value.cmp(&b.value));
            }
            SortBy::LevenshteinDistance => {
                sorted_items.sort_by(|a, b| {
                    let a_distance = levenshtein_distance(&prefix_str, &a.value);
                    let b_distance = levenshtein_distance(&prefix_str, &b.value);
                    a_distance.cmp(&b_distance)
                });
            }
            _ => (),
        }

        // Separate the results between hidden and non hidden
        let mut hidden: Vec<Suggestion> = vec![];
        let mut non_hidden: Vec<Suggestion> = vec![];

        for item in sorted_items.into_iter() {
            let item_path = Path::new(&item.value);

            if let Some(value) = item_path.file_name() {
                if let Some(value) = value.to_str() {
                    if value.starts_with('.') {
                        hidden.push(item);
                    } else {
                        non_hidden.push(item);
                    }
                }
            }
        }

        // Append the hidden folders to the non hidden vec to avoid creating a new vec
        non_hidden.append(&mut hidden);

        non_hidden
    }
}

pub fn directory_completion(
    span: nu_protocol::Span,
    partial: &str,
    cwd: &str,
    options: &CompletionOptions,
) -> Vec<(nu_protocol::Span, String)> {
    let original_input = partial;

    let (base_dir_name, partial) = partial_from(partial);

    let base_dir = nu_path::expand_path_with(&base_dir_name, cwd);

    // This check is here as base_dir.read_dir() with base_dir == "" will open the current dir
    // which we don't want in this case (if we did, base_dir would already be ".")
    if base_dir == Path::new("") {
        return Vec::new();
    }

    if let Ok(result) = base_dir.read_dir() {
        return result
            .filter_map(|entry| {
                entry.ok().and_then(|entry| {
                    if let Ok(metadata) = fs::metadata(entry.path()) {
                        if metadata.is_dir() {
                            let mut file_name = entry.file_name().to_string_lossy().into_owned();
                            if matches(&partial, &file_name, options) {
                                let mut path = if prepend_base_dir(original_input, &base_dir_name) {
                                    format!("{base_dir_name}{file_name}")
                                } else {
                                    file_name.to_string()
                                };

                                if entry.path().is_dir() {
                                    path.push(SEP);
                                    file_name.push(SEP);
                                }

                                // Fix files or folders with quotes or hash
                                if path.contains('\'')
                                    || path.contains('"')
                                    || path.contains(' ')
                                    || path.contains('#')
                                {
                                    path = format!("`{path}`");
                                }

                                Some((span, path))
                            } else {
                                None
                            }
                        } else {
                            None
                        }
                    } else {
                        None
                    }
                })
            })
            .collect();
    }

    Vec::new()
}
