use crate::{completion::feature::{get_dot_completion, include_path_completion}, server::LSPServer, sources::LSPSupport, utils::get_language_id_by_uri};
use log::info;
use ropey::{Rope, RopeSlice};
use tower_lsp::lsp_types::*;


pub fn completion(server: &LSPServer, params: &CompletionParams) -> Option<CompletionResponse> {
    let doc = &params.text_document_position;
    let uri = &params.text_document_position.text_document.uri;
    let pos = doc.position;
    let language_id = get_language_id_by_uri(uri);

    let file_id = server.srcs.get_id(uri).to_owned();
    server.srcs.wait_parse_ready(file_id, false);
    let file = server.srcs.get_file(file_id)?;
    let file = file.read().ok()?;
    let line_text = file.text.line(doc.position.line as usize);
    let token = get_completion_token(
        &file.text,
        line_text.clone(),
        doc.position,
    );

    // info!("trigger completion token: {}", token);
    let line_text = file.text.line(pos.line as usize);

    let response = match &params.context {
        Some(context) => match context.trigger_kind {
            CompletionTriggerKind::TRIGGER_CHARACTER => {
                let trigger_character = context.trigger_character.clone().unwrap();
                match trigger_character.as_str() {
                    "." => {
                        info!("trigger dot completion");
                        get_dot_completion(server, &line_text, uri, &pos, &language_id)
                    },
                    "$" => Some(CompletionList {
                        is_incomplete: false,
                        items: server.sys_tasks.clone(),
                    }),
                    "`" => Some(CompletionList {
                        is_incomplete: false,
                        items: server.directives.clone(),
                    }),
                    "/" => {
                        info!("trigger include");
                        include_path_completion(&doc.text_document.uri, &line_text, pos)
                    },
                    "\"" => {
                        info!("trigger include");
                        include_path_completion(&doc.text_document.uri, &line_text, pos)
                    }
                    _ => None,
                }
            }
            CompletionTriggerKind::TRIGGER_FOR_INCOMPLETE_COMPLETIONS => None,
            CompletionTriggerKind::INVOKED => {
                let mut comps = server.srcs.get_completions(
                    &token,
                    file.text.pos_to_byte(&doc.position),
                    &doc.text_document.uri,
                )?;
                
                // complete keywords
                comps.items.extend::<Vec<CompletionItem>>(
                    server.key_comps
                        .iter()
                        .filter(|x| x.label.starts_with(&token))
                        .cloned()
                        .collect(),
                );
                Some(comps)
            }
            _ => None,
        },
        None => {
            let trigger = prev_char(&file.text, &doc.position);
            match trigger {
                '.' => Some(server.srcs.get_dot_completions(
                    token.trim_end_matches('.'),
                    file.text.pos_to_byte(&doc.position),
                    &doc.text_document.uri,
                )?),
                '$' => Some(CompletionList {
                    is_incomplete: false,
                    items: server.sys_tasks.clone(),
                }),
                '`' => Some(CompletionList {
                    is_incomplete: false,
                    items: server.directives.clone(),
                }),
                _ => {
                    let mut comps = server.srcs.get_completions(
                        &token,
                        file.text.pos_to_byte(&doc.position),
                        &doc.text_document.uri,
                    )?;
                    comps.items.extend::<Vec<CompletionItem>>(
                        server.key_comps
                            .iter()
                            .filter(|x| x.label.starts_with(&token))
                            .cloned()
                            .collect(),
                    );
                    Some(comps)
                }
            }
        }
    };
    // eprintln!("comp response: {}", now.elapsed().as_millis());
    Some(CompletionResponse::List(response?))
}


/// get the previous non-whitespace character
fn prev_char(text: &Rope, pos: &Position) -> char {
    let char_idx = text.pos_to_char(pos);
    if char_idx > 0 {
        for i in (0..char_idx).rev() {
            let res = text.char(i);
            if !res.is_whitespace() {
                return res;
            }
        }
        ' '
    } else {
        ' '
    }
}

/// attempt to get the token the user was trying to complete, by
/// filtering out characters unneeded for name resolution
fn get_completion_token(text: &Rope, line: RopeSlice, pos: Position) -> String {
    let mut token = String::new();
    let mut line_iter = line.chars();
    for _ in 0..(line.utf16_cu_to_char(pos.character as usize)) {
        line_iter.next();
    }
    let mut c = line_iter.prev();
    //TODO: make this a regex
    while c.is_some()
        && (c.unwrap().is_alphanumeric()
            || c.unwrap() == '_'
            || c.unwrap() == '.'
            || c.unwrap() == '['
            || c.unwrap() == ']')
    {
        token.push(c.unwrap());
        c = line_iter.prev();
    }
    let mut result: String = token.chars().rev().collect();
    if result.contains('[') {
        let l_bracket_offset = result.find('[').unwrap_or(result.len());
        result.replace_range(l_bracket_offset.., "");
    }
    if &result == "." {
        // probably a instantiation, the token should be what we're instatiating
        let mut char_iter = text.chars();
        let mut token = String::new();
        for _ in 0..text.pos_to_char(&pos) {
            char_iter.next();
        }
        let mut c = char_iter.prev();

        // go to the last semicolon
        while c.is_some() && (c.unwrap() != ';') {
            c = char_iter.prev();
        }
        // go the the start of the next symbol
        while c.is_some() && !(c.unwrap().is_alphanumeric() || c.unwrap() == '_') {
            c = char_iter.next();
        }
        // then extract the next symbol
        while c.is_some() && (c.unwrap().is_alphanumeric() || c.unwrap() == '_') {
            token.push(c.unwrap());
            c = char_iter.next();
        }
        token
    } else {
        result
    }
}