//! Sort the given toml file based on SyntaxElements.
//!
//! Using a `Matcher` to specify the tables and values that have items that should be sorted
//! call `sort_toml_items` then compare the resulting tree using `SyntaxNodeExtTrait::deep_eq`.

use std::cmp::Ordering;

use rowan::{GreenNode, GreenNodeBuilder};

use super::tkn_tree::{SyntaxElement, SyntaxNode, SyntaxNodeExtTrait, TomlKind};

/// Each `Matcher` field when matched to a heading or key token
/// will be matched with `.contains()`.
pub struct Matcher<'a> {
    /// Toml headings with braces `[heading]`.
    pub heading: &'a [&'a str],
    /// Toml segmented heading without braces.
    pub segmented: &'a [&'a str],
    /// Toml heading with braces `[heading]` and the key
    /// of the array to sort.
    pub heading_key: &'a [(&'a str, &'a str)],
}

fn split_seg_last<S: AsRef<str>>(s: S) -> String {
    let open_close: &[char] = &['[', ']'];
    let heading = s.as_ref();

    heading
        .replace(open_close, "")
        .split('.')
        .last()
        .map(ToString::to_string)
        .unwrap()
}

pub fn sort_toml_items(root: &SyntaxNode, matcher: &Matcher<'_>) -> SyntaxNode {
    let mut builder = GreenNodeBuilder::new();
    builder.start_node(TomlKind::Root.into());

    for ele in sorted_tables_with_tokens(root, matcher.segmented) {
        match ele.kind() {
            TomlKind::Table => {
                // for [workspace] members = ...
                // this is heading and members is key.
                let (head, key): (Vec<_>, Vec<_>) = matcher.heading_key.iter().cloned().unzip();
                let node = ele.as_node().unwrap();
                if match_table(node, matcher.heading) {
                    add_sorted_table(node, &mut builder)
                } else if match_table(node, &head) {
                    add_table_sort_items(node, &mut builder, &key)
                } else {
                    add_element(ele, &mut builder)
                }
            }
            _ => add_element(ele, &mut builder),
        }
    }
    builder.finish_node();
    let green: GreenNode = builder.finish();
    SyntaxNode::new_root(green)
}

fn match_table(node: &SyntaxNode, headings: &[&str]) -> bool {
    match node.first_child().map(|n| n.kind()) {
        Some(TomlKind::Heading) => headings.iter().any(|h| node.token_text().contains(h)),
        _ => false,
    }
}

fn sorted_tables_with_tokens(
    root: &SyntaxNode,
    segmented: &[&str],
) -> impl Iterator<Item = SyntaxElement> {
    let kids = root.children_with_tokens().collect::<Vec<_>>();
    let pos = root
        .children_with_tokens()
        .enumerate()
        .filter(|(_, n)| n.as_node().map(|n| n.kind()) == Some(TomlKind::Table))
        .map(|(i, n)| {
            (
                i,
                n.as_node()
                    .unwrap()
                    .children()
                    .find(|n| n.kind() == TomlKind::Heading)
                    .map(|n| n.token_text()),
            )
        })
        .collect::<Vec<_>>();

    let mut tables = Vec::default();
    let mut start = 0;
    for (idx, key) in pos {
        let next_is_whitespace = kids
            .get(idx + 1)
            .map(|el| el.as_token().map(|t| t.kind()) == Some(TomlKind::Whitespace))
            == Some(true);

        let idx = if next_is_whitespace { idx + 1 } else { idx };

        tables.push((key, kids[start..=idx].to_vec()));
        start = idx + 1;
    }

    if start != kids.len() {
        tables.push((None, kids[start..].to_vec()))
    }

    for seg in segmented {
        #[rustfmt::skip]
        tables.sort_by(|chunk, other| {
            let chunk_matches_heading = chunk.0.as_ref()
                .map(|head| head.contains(&format!("[{}", seg))) == Some(true);
            let other_matches_heading = other.0.as_ref()
                .map(|head| head.contains(&format!("[{}", seg))) == Some(true);

            if chunk_matches_heading && other_matches_heading {
                chunk
                    .0
                    .as_ref()
                    .map(split_seg_last)
                    .cmp(&other.0.as_ref().map(split_seg_last))
            } else {
                Ordering::Equal
            }
        });
    }

    tables.into_iter().map(|p| p.1).flatten()
}

fn add_sorted_table(node: &SyntaxNode, builder: &mut GreenNodeBuilder) {
    builder.start_node(node.kind().into());

    if let Some(heading) = node.first_child() {
        add_node(&heading, builder);
    } else {
        unreachable!("table without heading")
    }

    // skip the table heading we just added
    let kv = node.children_with_tokens().skip(1).collect::<Vec<_>>();
    for ele in sort_key_value(&kv) {
        add_element(ele, builder);
    }

    builder.finish_node();
}

fn sort_key_value(kv: &[SyntaxElement]) -> Vec<SyntaxElement> {
    let pos = kv
        .iter()
        .enumerate()
        .filter(|(_, n)| n.as_node().map(|n| n.kind()) == Some(TomlKind::KeyValue))
        .map(|(i, n)| {
            (
                i,
                n.as_node()
                    .unwrap()
                    .children()
                    .find(|n| n.kind() == TomlKind::Key)
                    .map(|n| n.token_text()),
            )
        })
        .collect::<Vec<_>>();

    let mut keys = Vec::default();
    let mut start = 0_usize;
    for (found_idx, key) in pos {
        let idx = kv
            .iter()
            .skip(start)
            .enumerate()
            .take_while(|(count, n)| {
                // We group everything between key -> value pairs to *hopefully* maintain
                // comments
                n.as_node().map(|n| n.kind()) != Some(TomlKind::KeyValue) || *count == 0
            })
            .map(|(idx, _)| idx)
            .sum::<usize>()
            + found_idx;

        // At the end of a table the `start` may be greater than `idx`
        // this defers to the `if` block that adds the rest of the vec to `keys`
        if start > idx || idx > kv.len() {
            break;
        }

        keys.push((key, &kv[start..=idx]));
        start = idx + 1;
    }

    // if we did not reach the end of the table add the last whitespace/comments
    if start < kv.len() {
        keys.push((None, &kv[start..]))
    }

    keys.sort_by(|chunk, other| {
        if chunk.0.is_none() || other.0.is_none() {
            return Ordering::Equal;
        }
        chunk.0.cmp(&other.0)
    });
    keys.into_iter().map(|p| p.1).flatten().cloned().collect()
}

fn match_key(node: &SyntaxElement, keys: &[&str]) -> bool {
    match node
        .as_node()
        .map(|n| n.first_child().map(|n| n.kind()))
        .flatten()
    {
        Some(TomlKind::Key) => keys.iter().any(|h| {
            node.as_node()
                .unwrap()
                .first_child()
                .unwrap()
                .token_text()
                .contains(h)
                && node
                    .as_node()
                    .unwrap()
                    .children()
                    .find(|n| n.kind() == TomlKind::Value)
                    .map(|n| n.first_child().map(|n| n.kind() == TomlKind::Array))
                    .flatten()
                    == Some(true)
        }),
        _ => false,
    }
}

fn add_table_sort_items(node: &SyntaxNode, builder: &mut GreenNodeBuilder, key: &[&str]) {
    builder.start_node(node.kind().into());

    if let Some(heading) = node.first_child() {
        add_node(&heading, builder);
    } else {
        unreachable!("table without heading")
    }

    for ele in node.children_with_tokens().skip(1) {
        if match_key(&ele, key) {
            // this is a `KeyValue` node
            builder.start_node(ele.kind().into());
            for el in ele.as_node().unwrap().children_with_tokens() {
                match el {
                    SyntaxElement::Node(n) => match n.kind() {
                        TomlKind::Value => {
                            builder.start_node(TomlKind::Value.into());
                            if n.first_child().map(|n| n.kind()) == Some(TomlKind::Array) {
                                // the node type like TomlKind::Array
                                builder.start_node(TomlKind::Array.into());
                                builder
                                    .token(TomlKind::OpenBrace.into(), rowan::SmolStr::from("["));
                                for (end, sorted) in sort_items(n.first_child().unwrap()) {
                                    add_array_items(sorted, builder, end);
                                }
                                builder
                                    .token(TomlKind::CloseBrace.into(), rowan::SmolStr::from("]"));
                                builder.finish_node();
                            }
                            builder.finish_node();
                        }
                        _ => add_node(&n, builder),
                    },
                    SyntaxElement::Token(t) => builder.token(t.kind().into(), t.text().clone()),
                }
            }
            builder.finish_node();
        } else {
            add_element(ele, builder);
        }
    }

    builder.finish_node();
}

fn sort_items(node: SyntaxNode) -> Vec<(bool, SyntaxElement)> {
    // node is TomlKind::Array
    let children = node
        .children_with_tokens()
        .filter(|n| {
            let n = n.as_token().map(|n| n.kind());
            n != Some(TomlKind::CloseBrace) && n != Some(TomlKind::OpenBrace)
        })
        .collect::<Vec<_>>();

    let pos = children
        .iter()
        .enumerate()
        .filter(|(_, n)| n.as_node().map(|n| n.kind()) == Some(TomlKind::ArrayItem))
        .map(|(i, n)| {
            (
                i,
                n.as_node()
                    .unwrap()
                    .children()
                    .find(|n| n.kind() == TomlKind::Value)
                    .map(|n| n.token_text()),
            )
        })
        .collect::<Vec<_>>();

    let mut sorted = Vec::default();
    let mut current = 0;
    for (idx, key) in pos {
        let next_is_whitespace = children
            .get(idx + 1)
            .map(|el| el.as_token().map(|t| t.kind()) == Some(TomlKind::Whitespace))
            == Some(true);

        let idx = if next_is_whitespace { idx + 1 } else { idx };
        sorted.push((key, &children[current..=idx]));
        current = idx + 1;
    }
    if current != children.len() {
        sorted.push((None, &children[current..]))
    }
    sorted.sort_by(|chunk, other| {
        if chunk.0.is_none() {
            return Ordering::Equal;
        }
        if other.0.is_none() {
            return Ordering::Equal;
        }
        chunk.0.cmp(&other.0)
    });
    let end = sorted.len() - 1;
    sorted
        .into_iter()
        .flat_map(|p| p.1)
        .cloned()
        .enumerate()
        .map(|(i, el)| (i == end, el))
        .collect()
}

fn add_node(node: &SyntaxNode, builder: &mut GreenNodeBuilder) {
    builder.start_node(node.kind().into());

    for kid in node.children_with_tokens() {
        match kid {
            SyntaxElement::Node(n) => add_node(&n, builder),
            SyntaxElement::Token(t) => builder.token(t.kind().into(), t.text().clone()),
        }
    }

    builder.finish_node();
}

// TODO This for now alters the tokens, it checks if each element has a comma and space
// and removes it from the last element if it has comma and space ????
fn add_array_items(node: SyntaxElement, builder: &mut GreenNodeBuilder, end: bool) {
    match node {
        SyntaxElement::Node(node) => {
            if node.kind() == TomlKind::ArrayItem && !end && !node.token_text().contains("\n ") {
                match node
                    .children_with_tokens()
                    .map(|el| el.kind())
                    .collect::<Vec<TomlKind>>()
                    .as_slice()
                {
                    [.., TomlKind::Comma, TomlKind::Whitespace] => {
                        // this is a normal ArrayItem with comma and space
                        builder.start_node(node.kind().into());
                        for kid in node.children_with_tokens() {
                            match kid {
                                SyntaxElement::Node(n) => add_node(&n, builder),
                                SyntaxElement::Token(t) => {
                                    builder.token(t.kind().into(), t.text().clone())
                                }
                            }
                        }
                        builder.finish_node();
                    }
                    [.., _, _] | [_] | [] => {
                        // these have no comma or space and aren't the last ele so add comma...
                        builder.start_node(node.kind().into());
                        for kid in node.children_with_tokens() {
                            match kid {
                                SyntaxElement::Node(n) => add_node(&n, builder),
                                SyntaxElement::Token(t) => {
                                    builder.token(t.kind().into(), t.text().clone())
                                }
                            }
                        }
                        builder.token(TomlKind::Comma.into(), rowan::SmolStr::from(","));
                        builder.token(TomlKind::Whitespace.into(), rowan::SmolStr::from(" "));
                        builder.finish_node();
                    }
                }
            } else if end && !node.token_text().contains("\n ") {
                // removes last comma
                builder.start_node(node.kind().into());
                for kid in node.children_with_tokens() {
                    match kid {
                        SyntaxElement::Node(n) => add_node(&n, builder),
                        SyntaxElement::Token(t) => {
                            if t.kind() == TomlKind::Comma {
                                builder.finish_node();
                                return;
                            }
                            builder.token(t.kind().into(), t.text().clone())
                        }
                    }
                }
                builder.finish_node();
            } else {
                // we dont care what sequence of tokens are here just add em
                builder.start_node(node.kind().into());
                for kid in node.children_with_tokens() {
                    match kid {
                        SyntaxElement::Node(n) => add_node(&n, builder),
                        SyntaxElement::Token(t) => builder.token(t.kind().into(), t.text().clone()),
                    }
                }
                builder.finish_node();
            }
        }
        SyntaxElement::Token(t) => builder.token(t.kind().into(), t.text().clone()),
    }
}

fn add_element(node: SyntaxElement, builder: &mut GreenNodeBuilder) {
    match node {
        SyntaxElement::Node(node) => {
            builder.start_node(node.kind().into());
            for kid in node.children_with_tokens() {
                match kid {
                    SyntaxElement::Node(n) => add_node(&n, builder),
                    SyntaxElement::Token(t) => builder.token(t.kind().into(), t.text().clone()),
                }
            }
            builder.finish_node();
        }
        SyntaxElement::Token(t) => builder.token(t.kind().into(), t.text().clone()),
    }
}