use std::convert::TryFrom;
use std::io::Write;
use std::str::FromStr;

use clap::ArgMatches;
use chrono::{DateTime, Utc, Local, LocalResult, TimeZone};
use ansi_term::Color::Yellow;
use regex::Regex;

use crate::error::{Result, Error};
use crate::database::{Database, DBVersion};
use crate::formatters::Formatter;
use crate::config::Config;
use crate::timeparse::parse_time;
use crate::models::Entry;
use crate::regex::parse_regex;

use super::Command;

// ----------------------------------------------------------------
// Things that are general to all commands that display in some way
// ----------------------------------------------------------------

fn local_to_utc(t: DateTime<Utc>) -> Result<DateTime<Utc>> {
    let local_time = match Local.from_local_datetime(&t.naive_utc()) {
        LocalResult::None => return Err(Error::NoneLocalTime(t.naive_utc().to_string())),
        LocalResult::Single(t) => t,
        LocalResult::Ambiguous(t1, t2) => return Err(Error::AmbiguousLocalTime {
            orig: t.naive_utc().to_string(),
            t1: t1.naive_local(),
            t2: t2.naive_local(),
        }),
    };

    Ok(Utc.from_utc_datetime(&local_time.naive_utc()))
}

fn local_to_utc_vec(entries: Vec<Entry>) -> Result<Vec<Entry>> {
    entries
        .into_iter()
        .map(|e| {
            Ok(Entry {
                start: local_to_utc(e.start)?,
                end: e.end.map(|t| local_to_utc(t)).transpose()?,
                ..e
            })
        })
        .collect()
}

pub enum Sheet {
    All,
    Full,
    Sheet(String),
}

impl FromStr for Sheet {
    type Err = Error;

    fn from_str(name: &str) -> Result<Sheet> {
        Ok(match name {
            "all" => Sheet::All,
            "full" => Sheet::Full,
            name => Sheet::Sheet(name.into()),
        })
    }
}

pub fn entries_for_display<D, O, E>(
    start: Option<DateTime<Utc>>, end: Option<DateTime<Utc>>,
    sheet: Option<Sheet>, db: &mut D, out: &mut O, err: &mut E,
    format: Formatter, ids: bool, grep: Option<Regex>,
) -> Result<()>
where
    D: Database,
    O: Write,
    E: Write,
{
    let mut entries = match sheet {
        Some(Sheet::All) => db.entries_all_visible(start, end)?,
        Some(Sheet::Full) => db.entries_full(start, end)?,
        Some(Sheet::Sheet(name)) => db.entries_by_sheet(&name, start, end)?,
        None => {
            let current_sheet = db.current_sheet()?.unwrap_or("default".into());

            db.entries_by_sheet(&current_sheet, start, end)?
        }
    };

    if let Some(re) = grep {
        entries.retain(|e| re.is_match(e.note.as_ref().unwrap_or(&String::new())));
    }

    let (entries, needs_warning) = if let DBVersion::Timetrap = db.version()? {
        // this indicates that times in the database are specified in the
        // local time and need to be converted to utc before displaying

        (local_to_utc_vec(entries)?, true)
    } else {
        (entries, false)
    };

    format.print_formatted(
        entries,
        out,
        Utc::now(),
        ids,
    )?;

    if needs_warning {
        writeln!(
            err,
            "{} You are using the old timetrap format, it is advised that \
            you update your database using t migrate",
            Yellow.bold().paint("[WARNING]"),
        )?;
    }

    Ok(())
}

// ------------------------------------
// The actual implementation of display
// ------------------------------------

#[derive(Default)]
pub struct Args {
    ids: bool,
    start: Option<DateTime<Utc>>,
    end: Option<DateTime<Utc>>,
    format: Formatter,
    grep: Option<Regex>,
    sheet: Option<Sheet>,
}

impl<'a> TryFrom<&'a ArgMatches<'a>> for Args {
    type Error = Error;

    fn try_from(matches: &'a ArgMatches) -> Result<Args> {
        Ok(Args {
            ids: matches.is_present("ids"),
            start: matches.value_of("start").map(|s| parse_time(s)).transpose()?,
            end: matches.value_of("end").map(|s| parse_time(s)).transpose()?,
            format: matches.value_of("format").unwrap().parse()?,
            grep: matches.value_of("grep").map(parse_regex).transpose()?,
            sheet: matches.value_of("sheet").map(|s| s.parse()).transpose()?,
        })
    }
}

pub struct DisplayCommand { }

impl<'a> Command<'a> for DisplayCommand {
    type Args = Args;

    fn handle<D, O, E>(args: Self::Args, db: &mut D, out: &mut O, err: &mut E, _config: &Config) -> Result<()>
    where
        D: Database,
        O: Write,
        E: Write,
    {
        entries_for_display(args.start, args.end, args.sheet, db, out, err, args.format, args.ids, args.grep)
    }
}

#[cfg(test)]
mod tests {
    use chrono::TimeZone;
    use ansi_term::Color::Yellow;
    use pretty_assertions::assert_eq;

    use crate::database::SqliteDatabase;
    use crate::test_utils::PrettyString;

    use super::*;

    #[test]
    fn display_as_local_time_if_previous_version() {
        let args = Default::default();
        let mut db = SqliteDatabase::from_path("assets/test_old_db.db").unwrap();
        let mut out = Vec::new();
        let mut err = Vec::new();
        let config = Default::default();
        std::env::set_var("TZ", "UTC");

        DisplayCommand::handle(args, &mut db, &mut out, &mut err, &config).unwrap();

        assert_eq!(PrettyString(&String::from_utf8_lossy(&out)), PrettyString("Timesheet: default
    Day                Start      End        Duration Notes
    Tue Jun 29, 2021   06:26:49 - 07:26:52    1:00:03 lets do some rust
                                              1:00:03
    -------------------------------------------------------------------
    Total                                     1:00:03
"));

        assert_eq!(
            String::from_utf8_lossy(&err),
            format!("{} You are using the old timetrap format, it is advised that you update your database using t migrate\n", Yellow.bold().paint("[WARNING]")),
        );
    }

    #[test]
    fn correctly_use_utc_if_new_version() {
        assert!(false, "start with a newly created database");
        assert!(false, "correctly display times in local timezone");
    }

    #[test]
    fn filter_by_start() {
        let args = Args {
            format: Formatter::Csv,
            start: Some(Utc.ymd(2021, 6, 30).and_hms(10, 5, 0)),
            ..Default::default()
        };
        let mut db = SqliteDatabase::from_memory().unwrap();
        let mut out = Vec::new();
        let mut err = Vec::new();
        let config = Default::default();

        db.init().unwrap();

        db.entry_insert(Utc.ymd(2021, 6, 30).and_hms(10, 0, 0), None, Some("hola".into()), "default".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 6, 30).and_hms(10, 10, 0), None, Some("hola".into()), "default".into()).unwrap();

        DisplayCommand::handle(args, &mut db, &mut out, &mut err, &config).unwrap();

        assert_eq!(PrettyString(&String::from_utf8_lossy(&out)), PrettyString("start,end,note,sheet
2021-06-30T10:10:00Z,,hola,default
"));

        assert_eq!(
            String::from_utf8_lossy(&err),
            String::new(),
        );
    }

    #[test]
    fn filter_by_match() {
        let mut db = SqliteDatabase::from_memory().unwrap();
        let mut out = Vec::new();
        let mut err = Vec::new();

        db.init().unwrap();

        db.entry_insert(Utc.ymd(2021, 6, 30).and_hms(10, 0, 0), None, Some("hola".into()), "default".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 6, 30).and_hms(10, 10, 0), None, Some("adios".into()), "default".into()).unwrap();

        entries_for_display(None, None, None, &mut db, &mut out, &mut err, Formatter::Csv, true, Some("io".parse().unwrap())).unwrap();

        assert_eq!(PrettyString(&String::from_utf8_lossy(&out)), PrettyString("id,start,end,note,sheet
2,2021-06-30T10:10:00Z,,adios,default
"));

        assert_eq!(
            String::from_utf8_lossy(&err),
            String::new(),
        );
    }

    #[test]
    fn displays_grand_total_when_multiple_sheets() {
        unimplemented!()
    }
}