todo_lib 11.1.0

use chrono::{Duration, NaiveDate};

use crate::{human_date, todotxt};

#[derive(Debug)]
struct ExprItem<'a> {
    pub sign: char,
    pub val: &'a str,
}

/// Keeps a task tag values.
#[derive(Default, Clone)]
pub struct TaskTag {
    /// Tag name
    pub name: String,
    /// Tag raw value - the one that was passed in the command line by a user, e.g, `due+1`
    pub svalue: Option<String>,
    /// Calculated value. It is filled during calculation.
    pub dvalue: Option<NaiveDate>,
}

/// List of tags.
pub struct TaskTagList(Vec<TaskTag>);

/// The type of a tag value.
#[derive(Debug, PartialEq)]
pub enum TagValueType {
    /// The raw value defined by a user.
    Raw(String),
    /// Value calculated by this module (`ttdl add` case).
    /// Or the value read from the file (`ttdl edit` case).
    Calc(NaiveDate),
    /// The tag does not exists.
    None,
}

impl TaskTagList {
    /// Fills the tag list from the parsed task.
    pub fn from_task(task: &todotxt::Task) -> Self {
        let mut v = Vec::new();
        if let Some(dt) = task.due_date {
            let tg = TaskTag { name: "due".to_string(), dvalue: Some(dt), svalue: None };
            v.push(tg);
        }
        if let Some(dt) = task.create_date {
            let tg = TaskTag { name: "created".to_string(), dvalue: Some(dt), svalue: None };
            v.push(tg);
        }
        if let Some(dt) = task.threshold_date {
            let tg = TaskTag { name: "t".to_string(), dvalue: Some(dt), svalue: None };
            v.push(tg);
        }
        for (key, value) in task.tags.iter() {
            let tg = TaskTag { name: key.clone(), svalue: Some(value.clone()), dvalue: None };
            v.push(tg);
        }
        TaskTagList(v)
    }
    /// Fills the tag list from the raw string.
    pub fn from_str(s: &str, dt: NaiveDate) -> Self {
        let hmap = todotxt::extract_tags(s);
        let mut v = Vec::new();
        for (key, val) in hmap.iter() {
            let tg = TaskTag { name: key.to_string(), svalue: Some(val.to_string()), dvalue: None };
            v.push(tg);
        }
        let tg = TaskTag { name: "created".to_string(), dvalue: None, svalue: Some(todotxt::format_date(dt)) };
        v.push(tg);
        TaskTagList(v)
    }
    /// Change the tag value.
    /// Use the method after the value of the tag was calculated.
    pub fn set_tag(&mut self, tag: &str, value: NaiveDate) {
        for v in self.0.iter_mut() {
            if v.name.as_str() == tag {
                v.dvalue = Some(value);
                return;
            }
        }
    }
    /// Returns the value of a tag.
    pub fn tag_value(&self, tag: &str) -> TagValueType {
        for v in self.0.iter() {
            if v.name.as_str() == tag {
                if let Some(dt) = v.dvalue {
                    return TagValueType::Calc(dt);
                } else if let Some(ref s) = v.svalue {
                    return TagValueType::Raw(s.clone());
                }
            }
        }
        TagValueType::None
    }
}

// Full date format: YYYY-MM-DD
fn parse_full_date(s: &str) -> Option<&str> {
    let mut st = s;
    match s.find(|c: char| !c.is_ascii_digit()) {
        None => return None,
        Some(i) => {
            if i != 4 {
                return None;
            } else {
                st = &st[i..];
            }
        }
    }
    if !st.starts_with('-') {
        return None;
    }
    st = &st[1..];
    match st.find(|c: char| !c.is_ascii_digit()) {
        None => return None,
        Some(i) => {
            if i != 2 {
                return None;
            } else {
                st = &st[i..];
            }
        }
    }
    if !st.starts_with('-') {
        return None;
    }
    st = &st[1..];
    match st.find(|c: char| !c.is_ascii_digit()) {
        None => {
            if st.len() == 2 {
                Some(s)
            } else {
                None
            }
        }
        Some(i) => {
            if i != 2 {
                None
            } else {
                let l = "2020-01-01".len();
                let rest = &s[l..];
                if !rest.starts_with('-') && !rest.starts_with('+') {
                    return None;
                }
                Some(&s[..l])
            }
        }
    }
}

// Short date format: MM-DD
fn parse_short_date(s: &str) -> Option<&str> {
    let mut st = s;
    match s.find(|c: char| !c.is_ascii_digit()) {
        None => return None,
        Some(i) => {
            if i != 2 {
                return None;
            } else {
                st = &st[i..];
            }
        }
    }
    if !st.starts_with('-') {
        return None;
    }
    st = &st[1..];
    match st.find(|c: char| !c.is_ascii_digit()) {
        None => {
            if st.len() == 2 {
                Some(s)
            } else {
                None
            }
        }
        Some(i) => {
            if i != 2 {
                None
            } else {
                let l = "01-01".len();
                let rest = &s[l..];
                if !rest.starts_with('-') && !rest.starts_with('+') {
                    return None;
                }
                Some(&s[..l])
            }
        }
    }
}

// Single day format:DD
fn parse_single_day(s: &str) -> Option<&str> {
    match s.find(|c: char| !c.is_ascii_digit()) {
        None => {
            if s.len() < 3 {
                Some(s)
            } else {
                None
            }
        }
        Some(i) => {
            if i > 2 || i == 0 {
                None
            } else {
                let rest = &s[i..];
                if !rest.starts_with('-') && !rest.starts_with('+') {
                    return None;
                }
                Some(&s[..i])
            }
        }
    }
}

// Special date: tue, today, tomorrow etc
fn parse_special(s: &str) -> Option<&str> {
    let c = s.chars().next()?;
    if !c.is_ascii_lowercase() && !c.is_ascii_uppercase() {
        return None;
    }
    match s.find(|c: char| !c.is_ascii_lowercase() && !c.is_ascii_uppercase()) {
        None => Some(s),
        Some(idx) => {
            let rest = &s[idx..];
            if !rest.starts_with('-') && !rest.starts_with('+') { None } else { Some(&s[..idx]) }
        }
    }
}

// Duration: ##D (1-2 digits and duration type DWMY)
fn parse_duration(s: &str) -> Option<&str> {
    let c = s.chars().next()?;
    let durs = ['d', 'D', 'w', 'W', 'm', 'M', 'y', 'Y'];
    if c.is_ascii_digit() {
        let idxl = match s.find(|c: char| !c.is_ascii_digit()) {
            None => return Some(s),
            Some(i) => i,
        };
        let rest = &s[idxl..];
        if rest.starts_with('-') || rest.starts_with('+') {
            Some(&s[..idxl])
        } else if let Some(cc) = rest.chars().next() {
            if durs.contains(&cc) {
                if s.len() == idxl + 1 {
                    Some(s)
                } else {
                    let rest = &s[idxl + 1..];
                    if rest.starts_with('-') || rest.starts_with('+') { Some(&s[..idxl + 1]) } else { None }
                }
            } else {
                None
            }
        } else {
            None
        }
    } else if durs.contains(&c) {
        match s.find(|c: char| !c.is_ascii_lowercase() && !c.is_ascii_uppercase()) {
            None => {
                if s.len() == 1 {
                    Some(s)
                } else {
                    None
                }
            }
            Some(idx) => {
                let rest = &s[idx..];
                if rest.starts_with('-') || rest.starts_with('+') { Some(&s[..idx]) } else { None }
            }
        }
    } else {
        None
    }
}

fn parse_base_date(s: &str) -> Result<ExprItem<'_>, String> {
    if let Some(st) = parse_special(s) {
        return Ok(ExprItem { sign: '+', val: st });
    }
    if let Some(st) = parse_full_date(s) {
        return Ok(ExprItem { sign: '+', val: st });
    }
    if let Some(st) = parse_short_date(s) {
        return Ok(ExprItem { sign: '+', val: st });
    }
    if let Some(st) = parse_single_day(s) {
        return Ok(ExprItem { sign: '+', val: st });
    }
    Err("Failed to parse base date".to_string())
}

fn parse_expression(s: &str) -> Result<Vec<ExprItem<'_>>, String> {
    let mut items = Vec::new();
    let mut st = match parse_base_date(s) {
        Err(e) => return Err(e),
        Ok(ei) => {
            let sc = &s[ei.val.len()..];
            items.push(ei);
            sc
        }
    };
    while !st.is_empty() {
        if st.len() < 2 {
            return Err(format!("Incomplete expression: '{s}'"));
        }
        let c = match st.chars().next() {
            Some(cc) => cc,
            None => return Err("Internal error".to_string()),
        };
        if c != '-' && c != '+' {
            return Err(format!("Invalid character '{c}'"));
        }
        st = &st[1..];
        match parse_duration(st) {
            None => return Err(format!("Invalid duration: '{st}'")),
            Some(v) => {
                let ei = ExprItem { sign: c, val: v };
                st = &st[ei.val.len()..];
                items.push(ei);
            }
        }
    }
    Ok(items)
}

fn parse_abs_date(base: NaiveDate, s: &str, soon_days: u8) -> Result<NaiveDate, String> {
    match human_date::human_to_date(base, s, soon_days) {
        Ok(d) => Ok(d),
        Err(e) => {
            if e == human_date::NO_CHANGE {
                match NaiveDate::parse_from_str(s, "%Y-%m-%d") {
                    Ok(d) => Ok(d),
                    Err(e) => Err(format!("Invalid date [{s}]: {e}")),
                }
            } else {
                Err(e)
            }
        }
    }
}

fn calc_base(
    base: NaiveDate,
    s: &str,
    tags: &mut TaskTagList,
    soon_days: u8,
    counter: usize,
) -> Result<NaiveDate, String> {
    let mut dt = base;
    if s.find(|c: char| !c.is_ascii_lowercase() && !c.is_ascii_uppercase()).is_none() {
        // Special date case
        let spec = s.to_lowercase();
        let tval = tags.tag_value(spec.as_str());
        match tval {
            TagValueType::None => {
                dt = parse_abs_date(dt, s, soon_days)?;
            }
            TagValueType::Calc(d) => {
                dt = d;
            }
            TagValueType::Raw(s) => {
                let d = calc_expr(base, &s, tags, soon_days, counter + 1)?;
                tags.set_tag(&spec, d);
                dt = d;
            }
        }
    } else {
        // Absolute date
        dt = parse_abs_date(dt, s, soon_days)?;
    }
    Ok(dt)
}

fn calc_expr(
    base: NaiveDate,
    s: &str,
    tags: &mut TaskTagList,
    soon_days: u8,
    counter: usize,
) -> Result<NaiveDate, String> {
    if counter > 10 {
        return Err("Recursion stack overflow".to_string());
    }

    let items = parse_expression(s)?;
    if items.is_empty() {
        return Err("Empty expression".to_string());
    }

    let mut dt = base;
    for (idx, item) in items.iter().enumerate() {
        match idx {
            0 => {
                dt = calc_base(base, item.val, tags, soon_days, counter)?;
            }
            _ => {
                let rec_str = if item.val.find(|c: char| !c.is_ascii_digit()).is_none() {
                    format!("{0}d", item.val)
                } else {
                    item.val.to_string()
                };
                let rc = match todotxt::Recurrence::parse(&rec_str) {
                    Ok(r) => r,
                    Err(e) => {
                        return Err(format!("Invalid duration '{0}': {e}", item.val));
                    }
                };
                match rc.period {
                    todotxt::Period::Day => {
                        let dur = if item.sign == '-' {
                            Duration::days(-(rc.count as i64))
                        } else {
                            Duration::days(rc.count as i64)
                        };
                        dt += dur;
                    }
                    todotxt::Period::Week => {
                        let dur = if item.sign == '-' {
                            Duration::days(-(rc.count as i64) * 7)
                        } else {
                            Duration::days(rc.count as i64 * 7)
                        };
                        dt += dur;
                    }
                    todotxt::Period::Month => {
                        dt = human_date::add_months(dt, rc.count.into(), item.sign == '-');
                    }
                    todotxt::Period::Year => {
                        dt = human_date::add_years(dt, rc.count.into(), item.sign == '-');
                    }
                    _ => {}
                }
            }
        }
    }

    Ok(dt)
}

/// Calculate any expression using the existing tags.
/// NOTE: all expressions must follow the format:
///     <base-date> [<operation> <single-range>]?
/// where
///     base-date is either absolute date long or short format (YYYY-MM-DD) or and special date
///         like `today` or `sun`
///     operation is either `+` or `-`
///     single-range is the same format as recurrence #R (a number followed by a range type DWMY),
///         if range type is missing, it defaults to `d`=days
/// Examples:
///     `due+2` ==> 2 days after due date
///     `due+2d` ==> the same as above: 2 days after due date
///     `t-2w` ==> 2 weeks before threshold date
///     `due+1w+2d` ==> 1 week and 2 days after due date
pub fn calculate_expr(base: NaiveDate, s: &str, tags: &mut TaskTagList, soon_days: u8) -> Result<NaiveDate, String> {
    calc_expr(base, s, tags, soon_days, 1)
}

/// Calculates values of the main todo.txt tags.
/// The current list of such tags is short: `due` and `t`.
pub fn calculate_main_tags(base: NaiveDate, tags: &mut TaskTagList, soon_days: u8) -> Result<bool, String> {
    let mut anything_changed = false;
    for tag in ["due", "t"].into_iter() {
        let t = tags.tag_value(tag);
        if let TagValueType::Raw(s) = t {
            let cval = calculate_expr(base, &s, tags, soon_days)?;
            let fdate = todotxt::format_date(cval);
            if fdate.as_str() != s {
                tags.set_tag(tag, cval);
                anything_changed = true;
            }
        }
    }
    Ok(anything_changed)
}

/// Replaces the current tag values in a string with new calculated values.
/// The tag value is replaced only if the tag has TagValueType::Calc type.
/// The current list of replaced tags is short: `due` and `t`.
pub fn update_tags_in_str(tags: &TaskTagList, s: &str) -> String {
    let mut st = s.to_string();
    for tag in tags.0.iter() {
        if tag.name.as_str() != "due" && tag.name.as_str() != "t" {
            continue;
        }
        if let (Some(sval), Some(dval)) = (tag.svalue.clone(), tag.dvalue) {
            let old = format!("{0}:{sval}", tag.name);
            let new = format!("{0}:{1}", tag.name, todotxt::format_date(dval));
            todotxt::replace_word(&mut st, &old, &new);
        }
    }
    st
}

#[cfg(test)]
mod date_expr_test {
    use super::*;

    struct Test {
        txt: &'static str,
        err: bool,
        res: &'static str,
    }

    #[test]
    fn parse_full_date_test() {
        let tests: Vec<Test> = vec![
            Test { txt: "1999-20-20", err: false, res: "1999-20-20" },
            Test { txt: "1999-20-20+1d", err: false, res: "1999-20-20" },
            Test { txt: "1999-20-20-2", err: false, res: "1999-20-20" },
            Test { txt: "1999-20-20z", err: true, res: "" },
            Test { txt: "21999-20-20", err: true, res: "" },
            Test { txt: "1999-2-20", err: true, res: "" },
            Test { txt: "1999-20-0", err: true, res: "" },
            Test { txt: "19a9-20-20", err: true, res: "" },
            Test { txt: "1999-20-0a", err: true, res: "" },
            Test { txt: "cccccccccc", err: true, res: "" },
            Test { txt: "19992020", err: true, res: "" },
            Test { txt: "", err: true, res: "" },
            Test { txt: "-1999-20-20", err: true, res: "" },
        ];
        for test in tests.iter() {
            let r = parse_full_date(test.txt);
            match r {
                Some(rr) => {
                    if test.err {
                        assert!(false, "Test [{0}] must fail", test.txt);
                    }
                    assert_eq!(test.res, rr, "Failed [{0}]: {:?}", test.txt);
                }
                None => {
                    if !test.err {
                        assert!(false, "Test [{0}] must pass", test.txt);
                    }
                }
            }
        }
    }

    #[test]
    fn parse_special_test() {
        let tests: Vec<Test> = vec![
            Test { txt: "today", err: false, res: "today" },
            Test { txt: "Today", err: false, res: "Today" },
            Test { txt: "tODAY", err: false, res: "tODAY" },
            Test { txt: "tue", err: false, res: "tue" },
            Test { txt: "tue-2", err: false, res: "tue" },
            Test { txt: "today%2", err: true, res: "" },
            Test { txt: "2+today", err: true, res: "" },
        ];
        for test in tests.iter() {
            let r = parse_special(test.txt);
            match r {
                Some(rr) => {
                    if test.err {
                        assert!(false, "Test [{0}] must fail", test.txt);
                    }
                    assert_eq!(test.res, rr, "Failed [{0}]: {:?}", test.txt);
                }
                None => {
                    if !test.err {
                        assert!(false, "Test [{0}] must pass", test.txt);
                    }
                }
            }
        }
    }

    #[test]
    fn parse_short_date_test() {
        let tests: Vec<Test> = vec![
            Test { txt: "20-20", err: false, res: "20-20" },
            Test { txt: "20-20+1d", err: false, res: "20-20" },
            Test { txt: "20-20-2", err: false, res: "20-20" },
            Test { txt: "20-20z", err: true, res: "" },
            Test { txt: "320-20", err: true, res: "" },
            Test { txt: "2-20", err: true, res: "" },
            Test { txt: "20-0", err: true, res: "" },
            Test { txt: "2a-20", err: true, res: "" },
            Test { txt: "20-0a", err: true, res: "" },
            Test { txt: "ccccc", err: true, res: "" },
            Test { txt: "2020", err: true, res: "" },
            Test { txt: "", err: true, res: "" },
            Test { txt: "-20-20", err: true, res: "" },
        ];
        for test in tests.iter() {
            let r = parse_short_date(test.txt);
            match r {
                Some(rr) => {
                    if test.err {
                        assert!(false, "Test [{0}] must fail", test.txt);
                    }
                    assert_eq!(test.res, rr, "Failed [{0}]: {:?}", test.txt);
                }
                None => {
                    if !test.err {
                        assert!(false, "Test [{0}] must pass", test.txt);
                    }
                }
            }
        }
    }

    #[test]
    fn parse_duration_test() {
        let tests: Vec<Test> = vec![
            Test { txt: "w+1", err: false, res: "w" },
            Test { txt: "200d-1", err: false, res: "200d" },
            Test { txt: "15w", err: false, res: "15w" },
            Test { txt: "y", err: false, res: "y" },
            Test { txt: "2+3", err: false, res: "2" },
            Test { txt: "day", err: true, res: "" },
            Test { txt: "", err: true, res: "" },
            Test { txt: "a20", err: true, res: "" },
            Test { txt: "20days", err: true, res: "" },
            Test { txt: "20/4", err: true, res: "" },
            Test { txt: "20w/4", err: true, res: "" },
        ];
        for test in tests.iter() {
            let r = parse_duration(test.txt);
            match r {
                Some(rr) => {
                    if test.err {
                        assert!(false, "Test [{0}] must fail", test.txt);
                    }
                    assert_eq!(test.res, rr, "Failed [{0}]: {:?}", test.txt);
                }
                None => {
                    if !test.err {
                        assert!(false, "Test [{0}] must pass", test.txt);
                    }
                }
            }
        }
    }

    #[test]
    fn parse_expression_test() {
        struct ETest {
            txt: &'static str,
            l: usize,
            err: bool,
            last: &'static str,
        }
        let tests: Vec<ETest> = vec![
            ETest { txt: "2003-01-01", err: false, l: 1, last: "2003-01-01" },
            ETest { txt: "2003-01-01+2d", err: false, l: 2, last: "2d" },
            ETest { txt: "2003-01-01+2d-9", err: false, l: 3, last: "9" },
            ETest { txt: "2003-01-01+9-10m", err: false, l: 3, last: "10m" },
            ETest { txt: "tue+67", err: false, l: 2, last: "67" },
            ETest { txt: "2003-01-01+abcd", err: true, l: 1, last: "" },
            ETest { txt: "tue+tue", err: true, l: 1, last: "" },
            ETest { txt: "tue/2", err: true, l: 1, last: "" },
            ETest { txt: "2d", err: true, l: 1, last: "" },
        ];
        for test in tests.iter() {
            let r = parse_expression(test.txt);
            match r {
                Ok(rr) => {
                    if test.err {
                        assert!(false, "Test [{0}] must fail", test.txt);
                    }
                    assert_eq!(test.l, rr.len(), "{0} expected {1} items, got {2}", test.txt, test.l, rr.len());
                    assert_eq!(
                        test.last,
                        rr[rr.len() - 1].val,
                        "Failed [{0}]: {:?}, [{1}] != [{2}]",
                        test.txt,
                        test.last,
                        rr[rr.len() - 1].val
                    );
                }
                Err(e) => {
                    if !test.err {
                        assert!(false, "Test [{0}] must pass: {e:?}", test.txt);
                    }
                }
            }
        }
    }

    #[test]
    fn parse_str_expression_test() {
        struct ETest {
            txt: &'static str,
            err: bool,
            res: NaiveDate,
        }
        let tests: Vec<ETest> = vec![
            ETest { txt: "2021-05-07", err: false, res: NaiveDate::from_ymd_opt(2021, 5, 7).unwrap() },
            ETest { txt: "2021-05-07+10d", err: false, res: NaiveDate::from_ymd_opt(2021, 5, 17).unwrap() },
            ETest { txt: "2021-05-07+2w", err: false, res: NaiveDate::from_ymd_opt(2021, 5, 21).unwrap() },
            ETest { txt: "2021-05-07-7d", err: false, res: NaiveDate::from_ymd_opt(2021, 4, 30).unwrap() },
            ETest { txt: "2021-05-07-2m", err: false, res: NaiveDate::from_ymd_opt(2021, 3, 07).unwrap() },
            ETest { txt: "2021-05-07+1y", err: false, res: NaiveDate::from_ymd_opt(2022, 5, 07).unwrap() },
            ETest { txt: "2021-05-07+12d-2d", err: false, res: NaiveDate::from_ymd_opt(2021, 5, 17).unwrap() },
            ETest { txt: "2021-05-07+12d-1w", err: false, res: NaiveDate::from_ymd_opt(2021, 5, 12).unwrap() },
            ETest { txt: "today", err: false, res: NaiveDate::from_ymd_opt(2020, 3, 15).unwrap() },
            ETest { txt: "yesterday+2d", err: false, res: NaiveDate::from_ymd_opt(2020, 3, 16).unwrap() },
            ETest { txt: "first+1w", err: false, res: NaiveDate::from_ymd_opt(2020, 4, 8).unwrap() },
            ETest { txt: "due+1d", err: false, res: NaiveDate::from_ymd_opt(2020, 4, 9).unwrap() },
            ETest { txt: "t-1d", err: false, res: NaiveDate::from_ymd_opt(2020, 4, 3).unwrap() },
            ETest { txt: "extra+1w", err: false, res: NaiveDate::from_ymd_opt(2022, 9, 23).unwrap() },
            ETest { txt: "2021-05-07*2", err: true, res: NaiveDate::from_ymd_opt(2021, 5, 7).unwrap() },
            ETest { txt: "2021-05-07+1t", err: true, res: NaiveDate::from_ymd_opt(2021, 5, 7).unwrap() },
            ETest { txt: "someday", err: true, res: NaiveDate::from_ymd_opt(2021, 5, 7).unwrap() },
        ];

        let base = NaiveDate::from_ymd_opt(2020, 3, 15).unwrap();
        let task = todotxt::Task::parse("create something due:2020-04-08 t:due-4 extra:2022-09-16", base);
        let mut tlist = TaskTagList::from_task(&task);
        for (idx, test) in tests.iter().enumerate() {
            let d = calculate_expr(base, test.txt, &mut tlist, 8);
            if test.err {
                if d.is_ok() {
                    assert!(false, "Test {idx}.[{0}] must fail", test.txt);
                }
            } else {
                if d.is_err() {
                    assert!(false, "Test {idx}.[{0}] must pass: {1:?}", test.txt, d);
                } else {
                    assert_eq!(d.unwrap(), test.res, "Test {idx}.[{0}]", test.txt);
                }
            }
        }
    }
    #[test]
    fn tag_list_from_str_test() {
        struct ETest {
            txt: &'static str,
            count: usize,
            values: Vec<&'static str>,
        }
        let base = NaiveDate::from_ymd_opt(2020, 3, 15).unwrap();
        // Do not forget to add +1 - for "created"
        let tests: Vec<ETest> = vec![
            ETest { txt: "", count: 1, values: vec!["created", "2020-03-15"] },
            ETest {
                txt: "house due:2015-08-12 was done:due+5 t:2015-07-30 .",
                count: 4,
                values: vec!["created", "2020-03-15", "due", "2015-08-12", "done", "due+5", "t", "2015-07-30"],
            },
        ];
        for (idx, test) in tests.iter().enumerate() {
            let tlist = TaskTagList::from_str(test.txt, base);
            assert_eq!(test.count, tlist.0.len());
            for vidx in 0..test.values.len() / 2 {
                let v = tlist.tag_value(test.values[vidx * 2]);
                assert_eq!(
                    v,
                    TagValueType::Raw(test.values[vidx * 2 + 1].to_string()),
                    "{idx}. Tag [{0}] must get value [{1}] instead of [{2:?}]",
                    test.values[vidx * 2],
                    test.values[vidx * 2 + 1],
                    v
                );
            }
        }
    }
    #[test]
    fn tag_calculate_done_test() {
        struct ETest {
            txt: &'static str,
            is_err: bool,
            value: &'static str,
        }
        let base = NaiveDate::from_ymd_opt(2020, 3, 15).unwrap();
        // Do not forget to add +1 - for "created"
        let tests: Vec<ETest> = vec![
            ETest { txt: "", is_err: true, value: "" },
            ETest { txt: "no done tag, just t:2023-09-11", is_err: true, value: "" },
            ETest { txt: "exists normal done:2023-06-24 tag", is_err: false, value: "2023-06-24" },
            ETest { txt: "house due:2015-08-12 was done:due+5 t:2015-07-30 .", is_err: false, value: "2015-08-17" },
        ];
        for (idx, test) in tests.iter().enumerate() {
            let mut tlist = TaskTagList::from_str(test.txt, base);
            let res = calculate_expr(base, "done", &mut tlist, 7);
            match res {
                Err(e) => {
                    if !test.is_err {
                        assert!(false, "{idx}. The test must not fail. Got {0:?}", e);
                    }
                }
                Ok(d) => {
                    if test.is_err {
                        assert!(false, "{idx}. The test must fail");
                    } else {
                        let ds = todotxt::format_date(d);
                        assert_eq!(test.value, ds.as_str(), "Expected date: {0}, got {1}", test.value, d);
                    }
                }
            }
        }
    }
    #[test]
    fn tag_fix_str_test() {
        struct ETest {
            txt: &'static str,
            val: &'static str,
            fixed: bool,
        }
        let base = NaiveDate::from_ymd_opt(2020, 3, 15).unwrap();
        let tests: Vec<ETest> = vec![
            ETest { txt: "exists normal due:2023-06-24 tag", val: "exists normal due:2023-06-24 tag", fixed: false },
            ETest {
                txt: "house done:2015-08-12 was due:done-5 t:2015-07-30 .",
                val: "house done:2015-08-12 was due:2015-08-07 t:2015-07-30 .",
                fixed: true,
            },
        ];
        for (idx, test) in tests.iter().enumerate() {
            let mut tlist = TaskTagList::from_str(test.txt, base);
            let fixed = calculate_main_tags(base, &mut tlist, 7).unwrap();
            assert_eq!(fixed, test.fixed);
            let new_str = update_tags_in_str(&tlist, test.txt);
            assert_eq!(new_str.as_str(), test.val, "{idx}. Must be equal [{0}], got [{new_str}]", test.val);
        }
    }
}