use super::format::{date_text, excel_stamp, format_value, is_date_code};
use super::model::{Axis, Grouping, Kind, Pos, Series};
use super::plot::label;
use super::{Chart, El, FONT, LINE_W, MAX_CELLS, MAX_POINTS, MAX_RADAR_SERIES, MAX_SERIES, MAX_SPOKES, Rgb, fill_colour, int, measure, slot};

impl Chart {
    pub(super) fn parse(space: &El, theme: &[Rgb]) -> Option<Chart> {
        let chart = space.child("c:chart")?;
        let plot = chart.child("c:plotArea")?;
        let ty = plot.els().find(|e| Kind::of(&e.name).is_some())?;
        let kind = Kind::of(&ty.name)?;
        let scatter = kind == Kind::Scatter;
        let date1904 = space.child("c:date1904").is_some_and(|d| d.attr("val").is_none_or(truthy));
        let mut series = read_series(ty, scatter, theme);
        if series.is_empty() {
            return None;
        }
        let cats = ty.children("c:ser").find_map(|s| s.child("c:cat")).map(|c| labels(Some(c), MAX_POINTS, date1904)).unwrap_or_default();
        let n = if kind == Kind::Radar {
            series.iter().map(|s| s.values.len()).max().unwrap_or(0).max(cats.len()).min(MAX_SPOKES)
        } else if matches!(kind, Kind::Pie | Kind::Doughnut) {
            series.first().map_or(0, |s| s.values.len()).max(cats.len())
        } else {
            series.iter().map(|s| s.values.len()).max().unwrap_or(0).max(cats.len())
        };
        // Every series is padded to `n` points, so keep only as many as the cell budget holds.
        if let Some(keep) = MAX_CELLS.checked_div(n) {
            series.truncate(keep.max(1));
        }
        if kind == Kind::Radar {
            series.truncate(MAX_RADAR_SERIES);
        }
        let grouping = match ty.child("c:grouping").and_then(|g| g.attr("val")) {
            Some("stacked") if matches!(kind, Kind::Bar | Kind::Area | Kind::Line) => Grouping::Stacked,
            Some("percentStacked") if matches!(kind, Kind::Bar | Kind::Area | Kind::Line) => Grouping::Percent,
            _ => Grouping::Clustered,
        };
        let mut cats = cats;
        cats.resize(n, String::new());
        let radar_style = ty.child("c:radarStyle").and_then(|r| r.attr("val"));
        let type_labels = show_values(ty.child("c:dLbls"));
        for s in &mut series {
            s.values.resize(n, None);
            s.xs.resize(n, None);
            s.labels = Some(s.labels.or(type_labels).unwrap_or(false));
            if s.labels == Some(true) {
                s.raw = s.values.clone();
            }
        }
        if grouping == Grouping::Percent {
            to_percent(&mut series, n);
        }
        let (cat, val) = chart_axes(plot, scatter);
        let val_fmt = if grouping == Grouping::Percent {
            "0%".to_string()
        } else {
            val.fmt.clone().or_else(|| series.iter().find_map(|s| s.fmt.clone())).unwrap_or_else(|| "General".to_string())
        };
        let num = |n: &str| ty.child(n).and_then(|g| g.attr("val")).and_then(int);
        Some(Chart {
            kind,
            horizontal: kind == Kind::Bar && ty.child("c:barDir").and_then(|d| d.attr("val")) == Some("bar"),
            grouping,
            gap: num("c:gapWidth").unwrap_or(150).clamp(0, 500) as f32 / 100.0,
            overlap: num("c:overlap").unwrap_or(0).clamp(-100, 100) as f32 / 100.0,
            hole: num("c:holeSize").unwrap_or(50).clamp(10, 90) as f32 / 100.0,
            first_angle: num("c:firstSliceAng").unwrap_or(0).clamp(0, 360) as f64,
            radar_fill: radar_style == Some("filled"),
            radar_marks: radar_style == Some("marker"),
            vary: matches!(kind, Kind::Pie | Kind::Doughnut) && ty.child("c:varyColors").and_then(|v| v.attr("val")).is_none_or(truthy),
            n,
            cats,
            title: title_of(chart, &series),
            series,
            accents: (4..10).map(|i| slot(theme, i)).collect(),
            legend: legend_pos(chart),
            cat,
            val,
            text_size: text_size(space),
            val_fmt,
            date1904,
            plot_border: plot.child("c:spPr").and_then(|p| p.child("a:ln")).and_then(|l| fill_colour(l, theme)),
        })
    }

    pub(super) fn stacked(&self) -> bool {
        self.grouping != Grouping::Clustered
    }

    fn accent(&self, i: usize) -> Rgb {
        self.accents.get(i % 6).copied().unwrap_or(Rgb::BLACK)
    }

    /// Colour of series `j`: its own, else the accent its `c:idx` picks (as Word does; `c:order`
    /// doesn't matter), else the one its place in the file picks.
    pub(super) fn series_colour(&self, j: usize) -> Rgb {
        let s = self.series.get(j);
        s.and_then(|s| s.color).unwrap_or_else(|| self.accent(s.and_then(|s| s.idx).unwrap_or(j)))
    }

    /// Colour of point `i` of series `j`: its `c:dPt` override, else the varied accent (pie) or
    /// the series colour.
    pub(super) fn point_colour(&self, j: usize, i: usize) -> Rgb {
        if let Some(Some(c)) = self.series.get(j).and_then(|s| s.points.get(i)) {
            return *c;
        }
        if self.vary { self.accent(i) } else { self.series_colour(j) }
    }

    pub(super) fn legend_entries(&self) -> Vec<(String, Rgb)> {
        if matches!(self.kind, Kind::Pie | Kind::Doughnut) {
            return self
                .cats
                .iter()
                .enumerate()
                .map(|(i, c)| (if c.is_empty() { (i + 1).to_string() } else { c.clone() }, self.point_colour(0, i)))
                .collect();
        }
        self.series
            .iter()
            .enumerate()
            .map(|(j, s)| (if s.name.is_empty() { format!("Series {}", j + 1) } else { s.name.clone() }, self.series_colour(j)))
            .collect()
    }
}

/// The series of a chart type element, within the chart's cell budget.
pub(super) fn read_series(ty: &El, scatter: bool, theme: &[Rgb]) -> Vec<Series> {
    let mut budget = MAX_CELLS;
    let mut series = Vec::new();
    for ser in ty.children("c:ser").take(MAX_SERIES) {
        let s = Series::parse(ser, scatter, theme, budget.min(MAX_POINTS));
        budget = budget.saturating_sub(s.values.len().max(s.xs.len()));
        series.push(s);
    }
    series
}

/// Values as their share of each category's total (100% stacked charts).
fn to_percent(series: &mut [Series], n: usize) {
    for i in 0..n {
        let total: f64 = series.iter().map(|s| s.values.get(i).copied().flatten().map_or(0.0, f64::abs)).sum();
        for s in series.iter_mut() {
            if let Some(Some(v)) = s.values.get_mut(i) {
                *v = if total > 0.0 { *v / total } else { 0.0 };
            }
        }
    }
}

/// The category axis (scatter: the horizontal value axis) and the value axis of a plot area.
fn chart_axes(plot: &El, scatter: bool) -> (Axis, Axis) {
    let vals_ax: Vec<&El> = plot.children("c:valAx").collect();
    let horiz_pos = |a: &&El| matches!(a.child("c:axPos").and_then(|p| p.attr("val")), Some("b" | "t"));
    let (val_el, x_el) = if scatter {
        let x = vals_ax.iter().copied().find(horiz_pos).or_else(|| vals_ax.first().copied());
        let y = vals_ax.iter().copied().find(|a| !horiz_pos(a)).or_else(|| vals_ax.iter().copied().find(|a| Some(*a) != x));
        (y, x)
    } else {
        (vals_ax.first().copied(), None)
    };
    let cat_el = plot.els().find(|e| matches!(e.name.as_str(), "c:catAx" | "c:dateAx"));
    (axis(if scatter { x_el } else { cat_el }), axis(val_el))
}

/// The chart's title. An empty `c:title` shows the series name (Word's automatic title of a
/// one-series chart) unless the automatic title is deleted.
pub(super) fn title_of(chart: &El, series: &[Series]) -> Option<String> {
    let auto_deleted = chart.child("c:autoTitleDeleted").and_then(|a| a.attr("val")).is_some_and(truthy);
    let auto = if !auto_deleted && series.len() == 1 { series.first().map(|s| s.name.clone()).filter(|s| !s.is_empty()) } else { None };
    chart.child("c:title").and_then(|t| title_text(t).or(auto))
}

/// Whether a `c:dLbls` shows the values (`None` when there's none, or it doesn't say).
fn show_values(d: Option<&El>) -> Option<bool> {
    let d = d?;
    if d.child("c:delete").and_then(|e| e.attr("val")).is_some_and(truthy) {
        return Some(false);
    }
    d.child("c:showVal").map(|v| v.attr("val").is_none_or(truthy))
}

fn legend_pos(chart: &El) -> Option<Pos> {
    chart.child("c:legend").map(|l| match l.child("c:legendPos").and_then(|p| p.attr("val")).unwrap_or("r") {
        "l" => Pos::Left,
        "t" | "tr" => Pos::Top,
        "b" => Pos::Bottom,
        _ => Pos::Right,
    })
}

/// The chart's text size (its `c:txPr` default run size), points.
pub(super) fn text_size(space: &El) -> f32 {
    space
        .child("c:txPr")
        .and_then(|t| t.find("a:defRPr"))
        .and_then(|d| d.attr("sz"))
        .and_then(int)
        .map_or(FONT, |v| (v as f32 / 100.0).clamp(6.0, 24.0))
}

impl Series {
    fn parse(ser: &El, scatter: bool, theme: &[Rgb], cap: usize) -> Series {
        let name = ser.child("c:tx").and_then(|t| t.find("c:v")).map(|v| label(v.text().trim())).unwrap_or_default();
        let idx = ser.child("c:idx").and_then(|e| e.attr("val")).and_then(|v| v.trim().parse::<u32>().ok()).and_then(|v| usize::try_from(v).ok());
        let sp = ser.child("c:spPr");
        let ln = sp.and_then(|p| p.child("a:ln"));
        let marker = ser.child("c:marker").and_then(|m| m.child("c:spPr")).and_then(|p| fill_colour(p, theme));
        let color = sp.and_then(|p| fill_colour(p, theme)).or_else(|| ln.and_then(|l| fill_colour(l, theme))).or(marker);
        let line_w = ln.and_then(|l| l.attr("w")).and_then(|v| measure(v, 12_700.0)).map_or(LINE_W, |w| w.clamp(0.0, 20.0));
        let line = ln.is_none_or(|l| l.child("a:noFill").is_none());
        let (values, fmt) = numbers(ser.child(if scatter { "c:yVal" } else { "c:val" }), cap);
        let (mut xs, x_fmt) = if scatter { numbers(ser.child("c:xVal"), cap) } else { (Vec::new(), None) };
        if scatter && xs.is_empty() {
            xs = (1..=values.len()).map(|i| Some(i as f64)).collect();
        }
        let mut points = vec![None; values.len()];
        for dpt in ser.children("c:dPt") {
            let i = dpt.child("c:idx").and_then(|e| e.attr("val")).and_then(int).and_then(|i| usize::try_from(i).ok());
            let c = dpt.child("c:spPr").and_then(|p| fill_colour(p, theme));
            if let Some(slot) = i.and_then(|i| points.get_mut(i)) {
                *slot = c;
            }
        }
        let labels = show_values(ser.child("c:dLbls"));
        Series { name, idx, color, line_w, line, values, xs, points, fmt, x_fmt, labels, raw: Vec::new() }
    }
}

/// Longest number-format code honoured (the limit spreadsheet apps use); longer ones are ignored.
const MAX_FORMAT_CODE: usize = 255;

/// Category labels of a `c:cat` (string or number cache), capped. Numbers show in the cache's
/// format code (dates included); text and `General` numbers as they are stored.
pub(super) fn labels(el: Option<&El>, cap: usize, date1904: bool) -> Vec<String> {
    let Some(el) = el else { return Vec::new() };
    let Some(cache) = el.find("c:strCache").or_else(|| el.find("c:numCache")).or_else(|| el.find("c:strLit")).or_else(|| el.find("c:numLit")) else {
        return Vec::new();
    };
    let code =
        cache.child("c:formatCode").map(|f| f.text()).filter(|f| !f.is_empty() && f.len() <= MAX_FORMAT_CODE && !f.eq_ignore_ascii_case("General"));
    pts(cache, cap)
        .into_iter()
        .map(|p| {
            let text = p.unwrap_or_default();
            match (code.as_deref(), text.trim().parse::<f64>()) {
                (Some(code), Ok(v)) if v.is_finite() => label(&category_text(v, code, 1.0, date1904)),
                _ => label(&text),
            }
        })
        .collect()
}

/// A number in its format code: a date or time for date codes (serial days, from 1904 when
/// `date1904`), else as [`format_value`] with tick step `step`.
pub(super) fn category_text(v: f64, code: &str, step: f64, date1904: bool) -> String {
    match excel_stamp(v, date1904) {
        Some(t) if is_date_code(code) => date_text(t, code),
        _ => format_value(v, code, step),
    }
}

/// Values of a `c:val`-style element (number cache or literal), capped; with its format code.
pub(super) fn numbers(el: Option<&El>, cap: usize) -> (Vec<Option<f64>>, Option<String>) {
    let Some(cache) = el.and_then(|e| e.find("c:numCache").or_else(|| e.find("c:numLit"))) else {
        return (Vec::new(), None);
    };
    let fmt = cache.child("c:formatCode").map(|f| f.text()).filter(|f| !f.is_empty() && f.len() <= MAX_FORMAT_CODE);
    let vals = pts(cache, cap).into_iter().map(|p| p.and_then(|t| t.trim().parse::<f64>().ok()).filter(|v| v.is_finite())).collect();
    (vals, fmt)
}

/// The `c:pt` texts of a cache by index. Indexes and counts from the file are capped.
fn pts(cache: &El, cap: usize) -> Vec<Option<String>> {
    let declared = cache.child("c:ptCount").and_then(|c| c.attr("val")).and_then(int).unwrap_or(0).clamp(0, cap as i64) as usize;
    let mut out: Vec<Option<String>> = vec![None; declared];
    for p in cache.children("c:pt") {
        let Some(i) = p.attr("idx").and_then(int).and_then(|i| usize::try_from(i).ok()) else { continue };
        if i >= cap {
            continue;
        }
        if out.len() <= i {
            out.resize(i + 1, None);
        }
        if let Some(slot) = out.get_mut(i) {
            *slot = p.child("c:v").map(|v| v.text());
        }
    }
    out
}

pub(super) fn axis(a: Option<&El>) -> Axis {
    let Some(a) = a else { return Axis { deleted: true, ..Default::default() } };
    let scaling = a.child("c:scaling");
    let num =
        |n: &str| scaling.and_then(|s| s.child(n)).and_then(|e| e.attr("val")).and_then(|v| v.trim().parse::<f64>().ok()).filter(|v| v.is_finite());
    Axis {
        deleted: a.child("c:delete").and_then(|d| d.attr("val")).is_some_and(truthy),
        grid: a.child("c:majorGridlines").is_some(),
        line: a.child("c:spPr").and_then(|p| p.child("a:ln")).and_then(|l| l.child("a:noFill")).is_none(),
        mid: a.child("c:crossBetween").and_then(|c| c.attr("val")) == Some("midCat"),
        min: num("c:min"),
        max: num("c:max"),
        fmt: a
            .child("c:numFmt")
            .filter(|f| f.attr("sourceLinked") != Some("1"))
            .and_then(|f| f.attr("formatCode"))
            .filter(|f| f.len() <= MAX_FORMAT_CODE)
            .map(str::to_string),
    }
}

fn title_text(t: &El) -> Option<String> {
    let tx = t.child("c:tx")?;
    let s = match tx.child("c:rich") {
        Some(rich) => {
            let mut s = String::new();
            rich_into(rich, &mut s);
            s
        }
        None => tx.find("c:v").map(|v| v.text()).unwrap_or_default(),
    };
    let s = label(s.trim());
    (!s.is_empty()).then_some(s)
}

/// The `a:t` runs under an element, in order.
fn rich_into(e: &El, s: &mut String) {
    for c in e.els() {
        if c.name == "a:t" {
            s.push_str(&c.text());
        } else {
            rich_into(c, s);
        }
    }
}

fn truthy(v: &str) -> bool {
    matches!(v.trim(), "1" | "true")
}