use crate::*;

pub struct Table {
    /// The column definitions for this table.
    pub column_definitions: Vec<ColumnDefinition>,
    /// The content contained in the rows of the table. An individual [Line] is
    /// the contents of a single table cell, a group of cells forms a table row,
    /// a group of rows forms a vertical section of the table, with a separator
    /// intending to be drawn between each section, and a group of sections forms
    /// the table itself.
    /// Each row in the table is guaranteed to have the same number of columns
    /// as the table header.
    pub sections: Vec<Vec<Vec<Line>>>,
}

impl Table {
    pub fn try_from_strs(lines: &[&str]) -> Option<Self> {
        let mut lines = lines.into_iter();
        let column_definitions: Vec<ColumnDefinition> = {
            let names = split_trimmed_columns(lines.next()?)?
                .into_iter().map(|l| Line::from_str(l));
            let alignments = parse_alignments(lines.next()?)?;
            if names.len() != alignments.len() { return None }
            std::iter::zip(names, alignments).map(
                |(name, alignment)| ColumnDefinition { name, alignment } ).collect()
        };

        let mut sections = Vec::new();
        let mut current_section = Vec::new();

        for line in lines {
            if let Some(alignments) = parse_alignments(line) {
                if alignments.len() != column_definitions.len() { return None }
                sections.push(std::mem::take(&mut current_section))
            } else {
                let row: Vec<Line> = split_trimmed_columns(line)?
                    .into_iter().map(|c| Line::from_str(c)).collect();
                if row.len() != column_definitions.len() { return None }
                current_section.push(row);
            }
        }

        if !current_section.is_empty() {
            sections.push(std::mem::take(&mut current_section)); }
        Some( Self { column_definitions, sections })
    }
}

pub struct ColumnDefinition {
    /// The name of this column, shown in the header row of the table.
    pub name: Line,
    /// The alignment of the content in this column.
    pub alignment: ColumnAlignment,
}

pub enum ColumnAlignment {
    Left,
    Center,
    Right,
}

impl ColumnAlignment {
    pub fn from_str(cell: &str) -> Option<Self> {
        if !cell.chars().all(|c| c == ':' || c == '-') {
            return None }
        match (cell.starts_with(':'), cell.ends_with(':')) {
            (false, false) => Some(ColumnAlignment::Left),
            (false, true) => Some(ColumnAlignment::Right),
            (true, false) => Some(ColumnAlignment::Left),
            (true, true) => Some(ColumnAlignment::Center),
        }
    }
}


fn split_trimmed_columns(line: &str) -> Option<Vec<&str>> {
    Some(split_columns(line)?.into_iter().map(|s| s.trim()).collect())
}

fn split_columns(line: &str) -> Option<Vec<&str>> {
    if let Some(("", tail)) = line.split_once('|') {
        if let Some((head, "")) = tail.rsplit_once('|') {
            return Some(head.split('|').collect());
        }
    }
    return None;
}

fn parse_alignments(line: &str) -> Option<Vec<ColumnAlignment>> {
    let mut alignments = Vec::new();
    for cell in split_columns(line)? {
        alignments.push(ColumnAlignment::from_str(cell)?);
    }
    Some(alignments)
}