//! The edition dataset, vendored and read by hand (ADR-0011).
//!
//! `Problems.csv` is authoritative (ground-game, GROUND-WP-0002 T01). The
//! engine used to invent Problem values and suits; it reads them now.
//!
//! **Why not the `csv` crate.** It fits — 17,651 marginal lines against
//! AM-4b's 19,742 of headroom — and is refused anyway, because that is
//! 89% of everything the budget has left to read 20 rows, and the next
//! dependency would have 2,091 lines to live in. If this data ever grows
//! nested quoting, embedded newlines, or multiple dialects, that decision
//! is wrong and `csv` is the answer (ADR-0011 D1).

use crate::{SolutionCard, Suit};

/// One Problem as the edition prints it.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct EditionProblem {
    /// `hidden_priority`: 0 is the Surface Problem.
    pub priority: u8,
    pub value: u8,
    pub suit: Suit,
    /// `visibility == "Surface"` — dealt face up (GR-S01).
    pub surface: bool,
}

const CSV: &str = include_str!("../../../editions/ground-darvo-r0/Problems.csv");

/// Split one CSV record, honouring `"…"` quoting.
///
/// `problem_text` contains commas, which is the only reason this is not a
/// `split(',')`. Doubled quotes inside a quoted field are not handled and
/// do not occur; if they ever do, this returns the wrong field count and
/// `problems_of` fails loudly rather than mis-parsing.
fn fields(line: &str) -> Vec<String> {
    let mut out = Vec::new();
    let mut cur = String::new();
    let mut quoted = false;
    for c in line.chars() {
        match c {
            '"' => quoted = !quoted,
            ',' if !quoted => out.push(std::mem::take(&mut cur)),
            c => cur.push(c),
        }
    }
    out.push(cur);
    out
}

fn suit_of(s: &str) -> Option<Suit> {
    match s.trim() {
        "Clarify" => Some(Suit::Clarify),
        "Repair" => Some(Suit::Repair),
        "Boundary" => Some(Suit::Boundary),
        "Change" => Some(Suit::Change),
        _ => None,
    }
}

/// Every Problem of one scenario, ordered by `hidden_priority`.
///
/// Returns `Err` rather than an empty list when the data does not parse:
/// a loader that silently reads nothing would hand `setup` a game with no
/// Problems and look like a rules bug.
pub fn problems_of(scenario_id: &str) -> Result<Vec<EditionProblem>, String> {
    let mut lines = CSV.lines();
    let header = lines.next().ok_or("edition data is empty")?;
    let cols: Vec<String> = fields(header)
        .into_iter()
        .map(|c| c.trim_start_matches('\u{feff}').trim().to_string())
        .collect();
    let at = |name: &str| -> Result<usize, String> {
        cols.iter()
            .position(|c| c == name)
            .ok_or_else(|| format!("edition data has no column {name:?}"))
    };
    let (c_scn, c_pri, c_val, c_sol, c_vis) = (
        at("scenario_id")?,
        at("hidden_priority")?,
        at("point_value")?,
        at("required_solution")?,
        at("visibility")?,
    );

    let mut out = Vec::new();
    for line in lines.filter(|l| !l.trim().is_empty()) {
        let f = fields(line);
        if f.len() != cols.len() {
            return Err(format!(
                "edition row has {} fields, header has {}: {line}",
                f.len(),
                cols.len()
            ));
        }
        if f[c_scn].trim() != scenario_id {
            continue;
        }
        out.push(EditionProblem {
            priority: f[c_pri]
                .trim()
                .parse()
                .map_err(|_| format!("hidden_priority {:?} is not a number", f[c_pri]))?,
            value: f[c_val]
                .trim()
                .parse()
                .map_err(|_| format!("point_value {:?} is not a number", f[c_val]))?,
            suit: suit_of(&f[c_sol])
                .ok_or_else(|| format!("required_solution {:?} is not a suit", f[c_sol]))?,
            surface: f[c_vis].trim() == "Surface",
        });
    }
    if out.is_empty() {
        return Err(format!("edition data has no Problems for {scenario_id}"));
    }
    out.sort_by_key(|p| p.priority);
    Ok(out)
}

/// GR-S01 as ruled by ground-game 2026-08-04: **Surface always, plus
/// hidden priorities `1..=k`**, with k by seat band. Surface is never one
/// of the hidden slots.
///
/// Available points are therefore 6 / 9 / 12 with this edition's values —
/// the numbers ground-game ruled the thresholds 5 / 7 / 9 against.
pub fn hidden_depth(players: u8) -> Result<u8, String> {
    match players {
        2 => Ok(2),
        3..=4 => Ok(3),
        5..=6 => Ok(4),
        other => Err(format!("GR-S01: unsupported player count {other}")),
    }
}

/// The Problems dealt at `players` seats, Surface first.
pub fn deal(scenario_id: &str, players: u8) -> Result<Vec<EditionProblem>, String> {
    let k = hidden_depth(players)?;
    let all = problems_of(scenario_id)?;
    let dealt: Vec<EditionProblem> = all
        .into_iter()
        .filter(|p| p.surface || (p.priority >= 1 && p.priority <= k))
        .collect();
    Ok(dealt)
}

/// The core Solution deck, 6 per suit in canonical order (GR-S04).
pub fn solution_deck() -> Vec<SolutionCard> {
    [Suit::Clarify, Suit::Repair, Suit::Boundary, Suit::Change]
        .into_iter()
        .flat_map(|suit| std::iter::repeat_n(SolutionCard { suit }, 6))
        .collect()
}