use anyhow::{bail, Result};
use asyncgit::StatusItem;
use std::{
    collections::BTreeSet,
    convert::TryFrom,
    ffi::OsStr,
    ops::{Index, IndexMut},
    path::Path,
};

/// holds the information shared among all `FileTreeItem` in a `FileTree`
#[derive(Debug, Clone)]
pub struct TreeItemInfo {
    /// indent level
    pub indent: u8,
    /// currently visible depending on the folder collapse states
    pub visible: bool,
    /// just the last path element
    pub path: String,
    /// the full path
    pub full_path: String,
}

impl TreeItemInfo {
    const fn new(
        indent: u8,
        path: String,
        full_path: String,
    ) -> Self {
        Self {
            indent,
            visible: true,
            path,
            full_path,
        }
    }
}

/// attribute used to indicate the collapse/expand state of a path item
#[derive(PartialEq, Debug, Copy, Clone)]
pub struct PathCollapsed(pub bool);

/// `FileTreeItem` can be of two kinds
#[derive(PartialEq, Debug, Clone)]
pub enum FileTreeItemKind {
    Path(PathCollapsed),
    File(StatusItem),
}

/// `FileTreeItem` can be of two kinds: see `FileTreeItem` but shares an info
#[derive(Debug, Clone)]
pub struct FileTreeItem {
    pub info: TreeItemInfo,
    pub kind: FileTreeItemKind,
}

impl FileTreeItem {
    fn new_file(item: &StatusItem) -> Result<Self> {
        let item_path = Path::new(&item.path);
        let indent = u8::try_from(
            item_path.ancestors().count().saturating_sub(2),
        )?;

        let name = item_path
            .file_name()
            .map(OsStr::to_string_lossy)
            .map(|x| x.to_string());

        match name {
            Some(path) => Ok(Self {
                info: TreeItemInfo::new(
                    indent,
                    path,
                    item.path.clone(),
                ),
                kind: FileTreeItemKind::File(item.clone()),
            }),
            None => bail!("invalid file name {:?}", item),
        }
    }

    fn new_path(
        path: &Path,
        path_string: String,
        collapsed: bool,
    ) -> Result<Self> {
        let indent =
            u8::try_from(path.ancestors().count().saturating_sub(2))?;

        match path
            .components()
            .last()
            .map(std::path::Component::as_os_str)
            .map(OsStr::to_string_lossy)
            .map(String::from)
        {
            Some(path) => Ok(Self {
                info: TreeItemInfo::new(indent, path, path_string),
                kind: FileTreeItemKind::Path(PathCollapsed(
                    collapsed,
                )),
            }),
            None => bail!("failed to create item from path"),
        }
    }
}

impl Eq for FileTreeItem {}

impl PartialEq for FileTreeItem {
    fn eq(&self, other: &Self) -> bool {
        self.info.full_path.eq(&other.info.full_path)
    }
}

impl PartialOrd for FileTreeItem {
    fn partial_cmp(
        &self,
        other: &Self,
    ) -> Option<std::cmp::Ordering> {
        self.info.full_path.partial_cmp(&other.info.full_path)
    }
}

impl Ord for FileTreeItem {
    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
        self.info.path.cmp(&other.info.path)
    }
}

///
#[derive(Default)]
pub struct FileTreeItems {
    items: Vec<FileTreeItem>,
    file_count: usize,
}

impl FileTreeItems {
    ///
    pub(crate) fn new(
        list: &[StatusItem],
        collapsed: &BTreeSet<&String>,
    ) -> Result<Self> {
        let mut items = Vec::with_capacity(list.len());
        let mut paths_added = BTreeSet::new();

        for e in list {
            {
                let item_path = Path::new(&e.path);

                Self::push_dirs(
                    item_path,
                    &mut items,
                    &mut paths_added,
                    collapsed,
                )?;
            }

            items.push(FileTreeItem::new_file(e)?);
        }

        Ok(Self {
            items,
            file_count: list.len(),
        })
    }

    ///
    pub(crate) const fn items(&self) -> &Vec<FileTreeItem> {
        &self.items
    }

    ///
    pub(crate) fn len(&self) -> usize {
        self.items.len()
    }

    ///
    pub const fn file_count(&self) -> usize {
        self.file_count
    }

    ///
    pub(crate) fn find_parent_index(&self, index: usize) -> usize {
        let item_indent = &self.items[index].info.indent;
        let mut parent_index = index;
        while item_indent <= &self.items[parent_index].info.indent {
            if parent_index == 0 {
                return 0;
            }
            parent_index -= 1;
        }

        parent_index
    }

    fn push_dirs<'a>(
        item_path: &'a Path,
        nodes: &mut Vec<FileTreeItem>,
        paths_added: &mut BTreeSet<&'a Path>,
        collapsed: &BTreeSet<&String>,
    ) -> Result<()> {
        let mut ancestors =
            { item_path.ancestors().skip(1).collect::<Vec<_>>() };
        ancestors.reverse();

        for c in &ancestors {
            if c.parent().is_some() && !paths_added.contains(c) {
                paths_added.insert(c);
                let path_string =
                    String::from(c.to_str().expect("invalid path"));
                let is_collapsed = collapsed.contains(&path_string);
                nodes.push(FileTreeItem::new_path(
                    c,
                    path_string,
                    is_collapsed,
                )?);
            }
        }

        Ok(())
    }

    pub fn multiple_items_at_path(&self, index: usize) -> bool {
        let tree_items = self.items();
        let mut idx_temp_inner;
        if index + 2 < tree_items.len() {
            idx_temp_inner = index + 1;
            while idx_temp_inner < tree_items.len().saturating_sub(1)
                && tree_items[index].info.indent
                    < tree_items[idx_temp_inner].info.indent
            {
                idx_temp_inner += 1;
            }
        } else {
            return false;
        }

        tree_items[idx_temp_inner].info.indent
            == tree_items[index].info.indent
    }
}

impl IndexMut<usize> for FileTreeItems {
    fn index_mut(&mut self, idx: usize) -> &mut Self::Output {
        &mut self.items[idx]
    }
}

impl Index<usize> for FileTreeItems {
    type Output = FileTreeItem;

    fn index(&self, idx: usize) -> &Self::Output {
        &self.items[idx]
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use asyncgit::StatusItemType;

    fn string_vec_to_status(items: &[&str]) -> Vec<StatusItem> {
        items
            .iter()
            .map(|a| StatusItem {
                path: String::from(*a),
                status: StatusItemType::Modified,
            })
            .collect::<Vec<_>>()
    }

    #[test]
    fn test_simple() {
        let items = string_vec_to_status(&[
            "file.txt", //
        ]);

        let res =
            FileTreeItems::new(&items, &BTreeSet::new()).unwrap();

        assert_eq!(
            res.items,
            vec![FileTreeItem {
                info: TreeItemInfo {
                    path: items[0].path.clone(),
                    full_path: items[0].path.clone(),
                    indent: 0,
                    visible: true,
                },
                kind: FileTreeItemKind::File(items[0].clone())
            }]
        );

        let items = string_vec_to_status(&[
            "file.txt",  //
            "file2.txt", //
        ]);

        let res =
            FileTreeItems::new(&items, &BTreeSet::new()).unwrap();

        assert_eq!(res.items.len(), 2);
        assert_eq!(res.items[1].info.path, items[1].path);
    }

    #[test]
    fn test_folder() {
        let items = string_vec_to_status(&[
            "a/file.txt", //
        ]);

        let res = FileTreeItems::new(&items, &BTreeSet::new())
            .unwrap()
            .items
            .iter()
            .map(|i| i.info.full_path.clone())
            .collect::<Vec<_>>();

        assert_eq!(
            res,
            vec![String::from("a"), items[0].path.clone(),]
        );
    }

    #[test]
    fn test_indent() {
        let items = string_vec_to_status(&[
            "a/b/file.txt", //
        ]);

        let list =
            FileTreeItems::new(&items, &BTreeSet::new()).unwrap();
        let mut res = list
            .items
            .iter()
            .map(|i| (i.info.indent, i.info.path.as_str()));

        assert_eq!(res.next(), Some((0, "a")));
        assert_eq!(res.next(), Some((1, "b")));
        assert_eq!(res.next(), Some((2, "file.txt")));
    }

    #[test]
    fn test_indent_folder_file_name() {
        let items = string_vec_to_status(&[
            "a/b",   //
            "a.txt", //
        ]);

        let list =
            FileTreeItems::new(&items, &BTreeSet::new()).unwrap();
        let mut res = list
            .items
            .iter()
            .map(|i| (i.info.indent, i.info.path.as_str()));

        assert_eq!(res.next(), Some((0, "a")));
        assert_eq!(res.next(), Some((1, "b")));
        assert_eq!(res.next(), Some((0, "a.txt")));
    }

    #[test]
    fn test_folder_dup() {
        let items = string_vec_to_status(&[
            "a/file.txt",  //
            "a/file2.txt", //
        ]);

        let res = FileTreeItems::new(&items, &BTreeSet::new())
            .unwrap()
            .items
            .iter()
            .map(|i| i.info.full_path.clone())
            .collect::<Vec<_>>();

        assert_eq!(
            res,
            vec![
                String::from("a"),
                items[0].path.clone(),
                items[1].path.clone()
            ]
        );
    }

    #[test]
    fn test_multiple_items_at_path() {
        //0 a/
        //1   b/
        //2     c/
        //3       d
        //4     e/
        //5       f

        let res = FileTreeItems::new(
            &string_vec_to_status(&[
                "a/b/c/d", //
                "a/b/e/f", //
            ]),
            &BTreeSet::new(),
        )
        .unwrap();

        assert_eq!(res.multiple_items_at_path(0), false);
        assert_eq!(res.multiple_items_at_path(1), false);
        assert_eq!(res.multiple_items_at_path(2), true);
    }

    #[test]
    fn test_find_parent() {
        //0 a/
        //1   b/
        //2     c
        //3     d

        let res = FileTreeItems::new(
            &string_vec_to_status(&[
                "a/b/c", //
                "a/b/d", //
            ]),
            &BTreeSet::new(),
        )
        .unwrap();

        assert_eq!(res.find_parent_index(3), 1);
    }
}