use super::header_footer::HF_FIXED_SIDE_MARGIN;
use super::{
    Anchor, CellRef, Json, MAX_COLS, MAX_PAGES, MAX_ROWS, Orientation, PX_TO_PT, PageOrder, PrintSettings, RangeRef, Result, Sheet, Visibility,
    Workbook, bad, bool_param, split_sheet, str_param,
};

/// Cells in a page block above which only stored cells are visited (not every grid position).
pub(super) const DENSE_BLOCK: u64 = 60_000;

// ---------------------------------------------------------------- paper

/// Paper size in points (portrait) for a paper name; unknown names fall back to Letter.
pub fn paper_size(name: &str) -> (f32, f32) {
    known_paper(name).unwrap_or((612.0, 792.0))
}

/// Paper sizes in points, portrait. `B4`/`B5`/`B6` are the **JIS** sizes Japanese Excel and its
/// e-mail attachments use (257×364, 182×257 and 128×182 mm); the ISO B series stays reachable as
/// `B4 (ISO)`/`B5 (ISO)`/`B6 (ISO)`. The Japanese postcards and envelopes are the JIS ones too.
pub(super) fn known_paper(name: &str) -> Option<(f32, f32)> {
    // Spaces, hyphens, underscores and parentheses don't matter: `B5 (JIS)`, `b5-jis` and `b5`
    // are one name.
    let n = name.trim().to_ascii_lowercase().replace([' ', '-', '_', '(', ')'], "");
    Some(match n.as_str() {
        "letter" | "usletter" => (612.0, 792.0),
        "legal" | "uslegal" => (612.0, 1008.0),
        "a4" => (595.28, 841.89),
        "a3" => (841.89, 1190.55),
        "a5" => (419.53, 595.28),
        "a6" => (297.64, 419.53),
        "tabloid" | "11x17" => (792.0, 1224.0),
        "ledger" => (1224.0, 792.0),
        "executive" => (522.0, 756.0),
        "b4" | "b4jis" => (728.50, 1031.81),
        "b5" | "b5jis" => (515.91, 728.50),
        "b6" | "b6jis" => (362.83, 515.91),
        "b4iso" => (708.66, 1000.63),
        "b5iso" => (498.90, 708.66),
        "b6iso" => (354.33, 498.90),
        "japanesepostcard" | "postcard" => (283.46, 419.53),
        "japanesedoublepostcard" | "doublepostcard" => (419.53, 566.93),
        "japaneseenvelope#3" | "chou#3" => (340.16, 666.14),
        // 長形4号 is 90×205 mm; 90×225 mm is 長形40号, a different envelope, so it stays out.
        "japaneseenvelope#4" | "chou#4" => (255.12, 581.10),
        "japaneseenvelopekaku#2" | "kaku#2" => (680.31, 941.10),
        "japaneseenvelopekaku#3" | "kaku#3" => (612.28, 785.20),
        _ => return None,
    })
}

// ---------------------------------------------------------------- layout

/// The pagination of one sheet.
#[derive(Clone, Debug)]
pub struct SheetLayout {
    pub sheet: usize,
    pub settings: PrintSettings,
    pub page_w: f32,
    pub page_h: f32,
    /// Left, right, top, bottom, header, footer margins in points.
    pub margins: [f32; 6],
    pub scale: f32,
    pub area: RangeRef,
    pub row_bands: Vec<(u32, u32)>,
    pub col_bands: Vec<(u32, u32)>,
    /// Pages in print order: (row band, column band).
    pub pages: Vec<(usize, usize)>,
    pub title_rows: Option<(u32, u32)>,
    pub title_cols: Option<(u32, u32)>,
    /// Heading sizes in sheet pixels (0 when headings are off).
    pub heading_w: f32,
    pub heading_h: f32,
    /// Manual page breaks apply (they don't when the sheet is fitted to pages).
    pub manual_breaks: bool,
}

impl SheetLayout {
    pub(super) fn k(&self) -> f32 {
        PX_TO_PT * self.scale
    }
    pub(crate) fn avail(&self) -> (f32, f32) {
        let [l, r, t, b, ..] = self.margins;
        ((self.page_w - l - r).max(36.0), (self.page_h - t - b).max(36.0))
    }
    /// Left and right margins, in points, that header and footer sections line up with: the
    /// page's side margins with Align with Page Margins on, otherwise 0.7 inch on each side, at
    /// most a quarter of the page width.
    pub(crate) fn hf_sides(&self) -> (f32, f32) {
        if self.settings.hf_align_with_margins {
            (self.margins[0], self.margins[1])
        } else {
            let side = HF_FIXED_SIDE_MARGIN.min(self.page_w / 4.0);
            (side, side)
        }
    }
    /// Scale of header and footer text: the print scale with Scale with Document on, otherwise 1.
    pub(crate) fn hf_text_scale(&self) -> f32 {
        if self.settings.hf_scale_with_doc { self.scale } else { 1.0 }
    }
}

/// Options shared by the print commands.
#[derive(Clone, Debug, Default)]
pub struct PrintOptions {
    pub all_sheets: bool,
    pub range: Option<RangeRef>,
    pub fit_to_page: Option<bool>,
}

impl PrintOptions {
    pub(super) fn from_params(p: &Json, cmd: &str) -> Result<PrintOptions> {
        let all_sheets = match str_param(p, "sheets") {
            None | Some("active") => false,
            Some("all") | Some("workbook") => true,
            Some(other) => return Err(bad(cmd, format!("`sheets` must be active or all, not `{other}`"))),
        };
        let range = match str_param(p, "range").map(str::trim).filter(|r| !r.is_empty()) {
            Some(r) => Some(RangeRef::parse(split_sheet(r).1).ok_or_else(|| bad(cmd, format!("not a range: `{r}`")))?),
            None => None,
        };
        Ok(PrintOptions { all_sheets, range, fit_to_page: bool_param(p, "fitToPage") })
    }
}

/// The range a sheet prints: its print area, else the used range grown to cover drawing
/// objects. `None` when there is nothing to print.
pub fn print_range(sh: &Sheet) -> Option<RangeRef> {
    if let Some(a) = sh.print.print_area {
        return Some(trim_full(sh, a));
    }
    let mut r = sh.used_range();
    let mut grow = |a: &Anchor| {
        let x = sh.col_left(a.cell.col) + a.dx as f64;
        let y = sh.row_top(a.cell.row) + a.dy as f64;
        let end = CellRef::new(sh.row_at(y + a.height.max(0.0) as f64), sh.col_at(x + a.width.max(0.0) as f64));
        let ar = RangeRef::new(a.cell, end);
        r = Some(r.map_or(ar, |u| u.union(&ar)));
    };
    for c in &sh.charts {
        grow(&c.anchor);
    }
    for i in &sh.images {
        grow(&i.anchor);
    }
    for s in &sh.shapes {
        grow(&s.anchor);
    }
    // Printing starts at A1 like Excel when the data starts nearby? Excel prints from the first
    // used cell; keep the used range as is.
    r
}

/// Whole rows/columns are trimmed to the used range.
fn trim_full(sh: &Sheet, r: RangeRef) -> RangeRef {
    if !(r.is_full_cols() || r.is_full_rows()) {
        return r;
    }
    match sh.used_range() {
        Some(u) => r.intersection(&RangeRef::new(CellRef::new(0, 0), u.end)).unwrap_or(RangeRef::cell(r.start)),
        None => RangeRef::cell(r.start),
    }
}

/// Splits `start..=end` into bands whose sizes fit `avail(band_start)`; `breaks` force a new
/// band before a line. Stops after `cap` bands.
pub(super) fn bands(start: u32, end: u32, size: impl Fn(u32) -> f32, avail: impl Fn(u32) -> f32, breaks: &[u32], cap: usize) -> Vec<(u32, u32)> {
    let mut out = Vec::new();
    let mut cur = start;
    let mut used = 0.0f32;
    let mut room = avail(start);
    let mut line = start;
    loop {
        let sz = size(line);
        let manual = line > cur && breaks.binary_search(&line).is_ok();
        if line > cur && (manual || used + sz > room + 0.01) {
            out.push((cur, line - 1));
            if out.len() >= cap {
                return out;
            }
            cur = line;
            used = 0.0;
            room = avail(line);
        }
        used += sz;
        if line >= end {
            break;
        }
        line += 1;
    }
    out.push((cur, end));
    out
}

fn title_span(t: Option<(u32, u32)>, max: u32) -> Option<(u32, u32)> {
    let (a, b) = t?;
    let (a, b) = (a.min(b), a.max(b));
    if a >= max {
        return None;
    }
    // Repeated titles are capped (Excel needs them to fit on a page anyway).
    Some((a, b.min(max - 1).min(a.saturating_add(499))))
}

/// Paginates one sheet.
pub fn layout_sheet(wb: &Workbook, si: usize, opts: &PrintOptions, range_override: Option<RangeRef>) -> Option<SheetLayout> {
    let sh = wb.sheet(si)?;
    let st = sh.print.clone();
    let (mut pw, mut ph) = paper_size(&st.paper);
    if st.orientation == Orientation::Landscape {
        std::mem::swap(&mut pw, &mut ph);
    }
    let inch = |i: usize| st.margins.get(i).copied().filter(|v| v.is_finite()).unwrap_or(0.5).clamp(0.0, 20.0) * 72.0;
    let mut margins = [inch(0), inch(1), inch(2), inch(3), inch(4), inch(5)];
    // Keep at least an inch of printable space.
    for (a, b, total) in [(0usize, 1usize, pw), (2, 3, ph)] {
        let sum = margins[a] + margins[b];
        if total - sum < 72.0 {
            let f = ((total - 72.0).max(0.0)) / sum.max(1.0);
            margins[a] *= f;
            margins[b] *= f;
        }
    }
    let area = match range_override {
        Some(r) => trim_full(sh, r),
        None => print_range(sh).unwrap_or(RangeRef::cell(CellRef::new(0, 0))),
    };
    let title_rows = title_span(st.title_rows, MAX_ROWS);
    let title_cols = title_span(st.title_cols, MAX_COLS);
    let digits = format!("{}", area.end.row + 1).len() as f32;
    let (heading_w, heading_h) = if st.headings { (10.0 + 7.0 * digits, sh.default_row_height.clamp(10.0, 60.0)) } else { (0.0, 0.0) };
    let fit = match opts.fit_to_page {
        Some(true) => Some((1u16, 1u16)),
        Some(false) => None,
        None => st.fit_to.filter(|(w, h)| *w > 0 || *h > 0),
    };
    let mut lay = SheetLayout {
        sheet: si,
        settings: st.clone(),
        page_w: pw,
        page_h: ph,
        margins,
        scale: (st.scale.clamp(10, 400) as f32) / 100.0,
        area,
        row_bands: vec![],
        col_bands: vec![],
        pages: vec![],
        title_rows,
        title_cols,
        heading_w,
        heading_h,
        manual_breaks: fit.is_none(),
    };
    let paginate = |lay: &mut SheetLayout, manual: bool| {
        lay.manual_breaks = manual;
        (lay.row_bands, lay.col_bands) = split_bands(sh, lay, MAX_PAGES);
        lay.pages = page_sequence(lay.row_bands.len(), lay.col_bands.len(), lay.settings.page_order, MAX_PAGES);
    };
    match fit {
        Some((fw, fh)) => {
            let total_w: f32 = (area.start.col..=area.end.col).map(|c| sh.col_width(c)).sum::<f32>() + heading_w;
            let total_h: f32 = if area.height() > 200_000 {
                f32::INFINITY
            } else {
                (area.start.row..=area.end.row).map(|r| sh.row_height(r)).sum::<f32>() + heading_h
            };
            let (aw, ah) = lay.avail();
            let sw = if fw > 0 { aw * fw as f32 / (total_w * PX_TO_PT).max(1.0) } else { f32::INFINITY };
            let sh_ = if fh > 0 { ah * fh as f32 / (total_h * PX_TO_PT).max(1.0) } else { f32::INFINITY };
            lay.scale = sw.min(sh_).min(1.0).clamp(0.1, 1.0);
            for _ in 0..40 {
                paginate(&mut lay, false);
                let ok_w = fw == 0 || lay.col_bands.len() <= fw as usize;
                let ok_h = fh == 0 || lay.row_bands.len() <= fh as usize;
                if (ok_w && ok_h) || lay.scale <= 0.1 {
                    break;
                }
                lay.scale = (lay.scale * 0.97).max(0.1);
            }
        }
        None => paginate(&mut lay, true),
    }
    Some(lay)
}

/// The pages of a sheet `rows` pages tall and `cols` pages wide as (row band, column band), in
/// print order, at most `cap` of them: down each column of pages, then over to the next (Excel's
/// default), or over each row of pages, then down to the next.
pub(crate) fn page_sequence(rows: usize, cols: usize, order: PageOrder, cap: usize) -> Vec<(usize, usize)> {
    let (outer, inner) = match order {
        PageOrder::DownThenOver => (cols, rows),
        PageOrder::OverThenDown => (rows, cols),
    };
    (0..outer)
        .flat_map(|o| {
            (0..inner).map(move |i| match order {
                PageOrder::DownThenOver => (i, o),
                PageOrder::OverThenDown => (o, i),
            })
        })
        .take(cap)
        .collect()
}

/// Inclusive-start/end index spans of the pages along one axis.
pub(crate) type Bands = Vec<(u32, u32)>;

/// Splits a layout's area into row and column bands that fit its pages (at most `cap` of each),
/// honouring manual breaks (when `lay.manual_breaks`), print headings and repeated titles. The
/// one pagination rule shared by printing, PDF export, Page Break Preview and Page Layout view.
pub(crate) fn split_bands(sh: &Sheet, lay: &SheetLayout, cap: usize) -> (Bands, Bands) {
    let k = lay.k();
    let (aw, ah) = lay.avail();
    let (aw, ah) = (aw / k, ah / k);
    let st = &lay.settings;
    let mut rb: Vec<u32> = if lay.manual_breaks { st.row_breaks.clone() } else { vec![] };
    let mut cb: Vec<u32> = if lay.manual_breaks { st.col_breaks.clone() } else { vec![] };
    rb.sort_unstable();
    cb.sort_unstable();
    let (title_rows, title_cols) = (lay.title_rows, lay.title_cols);
    let title_h = |start: u32| -> f32 {
        match title_rows {
            Some((a, b)) if a < start => (a..=b.min(start - 1)).map(|r| sh.row_height(r)).sum(),
            _ => 0.0,
        }
    };
    let title_w = |start: u32| -> f32 {
        match title_cols {
            Some((a, b)) if a < start => (a..=b.min(start - 1)).map(|c| sh.col_width(c)).sum(),
            _ => 0.0,
        }
    };
    let area = lay.area;
    let rows = bands(area.start.row, area.end.row, |r| sh.row_height(r), |start| (ah - lay.heading_h - title_h(start)).max(1.0), &rb, cap);
    let cols = bands(area.start.col, area.end.col, |c| sh.col_width(c), |start| (aw - lay.heading_w - title_w(start)).max(1.0), &cb, cap);
    (rows, cols)
}

/// Lays out every sheet a print command covers.
pub fn layouts(wb: &Workbook, opts: &PrintOptions) -> Vec<SheetLayout> {
    let mut out = Vec::new();
    let mut pages = 0usize;
    let sheets: Vec<usize> = if opts.all_sheets {
        (0..wb.sheets.len()).filter(|i| wb.sheet(*i).is_some_and(|s| s.visibility == Visibility::Visible)).collect()
    } else {
        vec![wb.active_sheet()]
    };
    for si in sheets {
        if pages >= MAX_PAGES {
            break;
        }
        let ovr = if si == wb.active_sheet() { opts.range } else { None };
        if opts.all_sheets && ovr.is_none() && wb.sheet(si).is_some_and(|s| print_range(s).is_none()) {
            continue;
        }
        if let Some(mut l) = layout_sheet(wb, si, opts, ovr) {
            l.pages.truncate(MAX_PAGES - pages);
            pages += l.pages.len();
            out.push(l);
        }
    }
    if out.is_empty() && opts.all_sheets {
        out.extend(layout_sheet(wb, wb.active_sheet(), opts, None));
    }
    out
}

/// Segments of a page along one axis: repeated titles (before the band) then the band.
pub(super) fn segments(titles: Option<(u32, u32)>, band: (u32, u32)) -> Vec<(u32, u32)> {
    let mut v = Vec::new();
    if let Some((a, b)) = titles
        && a < band.0
    {
        v.push((a, b.min(band.0 - 1)));
    }
    v.push(band);
    v
}

pub(super) fn seg_size(sh: &Sheet, seg: (u32, u32), rows: bool) -> f32 {
    if rows { (seg.0..=seg.1).map(|r| sh.row_height(r)).sum() } else { (seg.0..=seg.1).map(|c| sh.col_width(c)).sum() }
}