use db;
use util;

use clap;

pub struct Command {
    query: String,
    tsv: bool,
}

pub fn subcommand<'a, 'b>() -> clap::App<'a, 'b> {
    clap::SubCommand::with_name("sql")
        .about("Run a query against the local database")
        .arg(
            clap::Arg::with_name("query")
                .required(true)
                .help("query to run")
        )
        .arg(
            clap::Arg::with_name("tsv")
                .long("tsv")
                .help("format output as tsv")
        )
}

impl Command {
    pub fn new<'a>(matches: &clap::ArgMatches<'a>) -> Command {
        Command {
            query: matches.value_of("query").unwrap().to_string(),
            tsv: matches.is_present("tsv"),
        }
    }
}

impl super::Command for Command {
    fn run(&self) -> failure::Fallible<()> {
        let db = db::DB::new(&util::db_path()?)?;

        let rows_cell = std::cell::Cell::new(Some(vec![]));
        let cols = db.query(&self.query, |row| {
            let display_row: Vec<String> = (0..row.column_count())
                .map(|i| row.get_raw(i))
                .map(|v| format_value(&v))
                .collect();
            let mut rows = rows_cell.replace(None).unwrap();
            rows.push(display_row);
            rows_cell.replace(Some(rows));
        })?;

        let rows = rows_cell.into_inner().unwrap();

        if self.tsv {
            print_tsv(&rows);
        }
        else {
            print_table(&cols, &rows);
        }

        Ok(())
    }
}

fn print_table(cols: &[String], rows: &[Vec<String>]) {
    let widths = column_widths(&cols, &rows);

    print_row(&widths, &cols);
    let border: Vec<String> = widths.iter().map(|l| "-".repeat(*l)).collect();
    println!("{}", &border.join("-+-"));

    for row in rows {
        print_row(&widths, &row);
    }
}

fn print_tsv(rows: &[Vec<String>]) {
    for row in rows {
        println!("{}", row.join("\t"));
    }
}

fn format_value(v: &rusqlite::types::ValueRef) -> String {
    match v {
        rusqlite::types::ValueRef::Null => "null".to_string(),
        rusqlite::types::ValueRef::Integer(i) => format!("{}", i),
        rusqlite::types::ValueRef::Real(f) => format!("{}", f),
        rusqlite::types::ValueRef::Text(s) => format!("{}", s),
        rusqlite::types::ValueRef::Blob(b) => format!("{:?}", b),
    }
}

fn column_widths(cols: &[String], rows: &[Vec<String>]) -> Vec<usize> {
    let mut max_widths: Vec<usize> = cols.iter().map(|s| s.len()).collect();
    for row in rows {
        for (i, col) in row.iter().enumerate() {
            if col.len() > max_widths[i] {
                max_widths[i] = col.len();
            }
        }
    }
    max_widths
}

fn print_row(widths: &[usize], row: &[String]) {
    let fixed_width_row: Vec<String> = row
        .iter()
        .zip(widths.iter())
        .map(|(s, width)| format!("{:width$}", s, width=width))
        .collect();
    println!("{}", &fixed_width_row.join(" | "));
}