varar-core 0.6.1

//! The planner — port of `plan.ts` / `Plan.java`. Plans each text-bearing block
//! via the matcher, lifts block offsets to source spans, attaches trailing
//! table/fence nodes, handles the ```` ```error ```` fence, expands header-bound
//! tables into one example per row, and collects diagnostics.

use crate::ast::{Block, Fence, Row, SegmentOffset, Table, VarDoc};
use crate::cell_diff::RowCheck;
use crate::diagnostics::{Diagnostic, ambiguous_match, error_fence_without_step};
use crate::matcher::{Hit, ParamSpan, ResolvedSteps, find_hits, resolve_hits};
use crate::offsets::{java_trim, utf16_len};
use crate::registry::{FormatFn, Registry, StepRegistration};
use crate::sentences::split_sentences;
use crate::span::Span;
use crate::value::Value;
use regex::Regex;
use std::collections::BTreeMap;
use std::rc::Rc;
use std::sync::LazyLock;

/// The result of planning a whole [`VarDoc`].
pub struct ExecutionPlan {
    pub var_doc: VarDoc,
    pub examples: Vec<PlannedExample>,
    pub diagnostics: Vec<Diagnostic>,
}

/// One matched-and-runnable example.
pub struct PlannedExample {
    pub name: String,
    pub scope_stack: Vec<String>,
    pub span: Span,
    pub steps: Vec<PlannedStep>,
    pub header_binding: Option<HeaderBinding>,
    pub row_checks: Option<Vec<RowCheck>>,
    pub expected_outcome: Option<String>,
    pub expected_error_message: Option<String>,
}

/// The binding paragraph shared by every row of a header-bound table.
pub struct HeaderBinding {
    pub match_span: Span,
    pub param_spans: Vec<Span>,
    pub step_def: Rc<StepRegistration>,
}

/// One matched step: text, source span, captured-parameter spans, args, and
/// attachments. `formats` aligns 1:1 with `args`.
#[derive(Clone)]
pub struct PlannedStep {
    pub text: String,
    pub match_span: Span,
    pub param_spans: Vec<Span>,
    pub step_def: Rc<StepRegistration>,
    pub args: Vec<Value>,
    pub formats: Vec<Option<FormatFn>>,
    pub data_table: Option<Table>,
    pub doc_string: Option<Fence>,
}

static WHITESPACE_RE: LazyLock<Regex> = LazyLock::new(|| Regex::new(r"\s+").unwrap());
static WORD_CHAR_RE: LazyLock<Regex> = LazyLock::new(|| Regex::new(r"^[\p{L}\p{N}_]$").unwrap());

/// Plans `doc` against `registry`. Port of `plan()`.
pub fn plan(doc: &VarDoc, registry: &Registry) -> ExecutionPlan {
    let source = &doc.source;
    let mut examples = Vec::new();
    let mut diagnostics = Vec::new();

    for ex in &doc.examples {
        let mut had_ambiguous = false;
        let body = &ex.body;

        // Pass 1: plan each text-bearing block, collecting steps per body index.
        let mut steps_by_block: BTreeMap<usize, Vec<PlannedStep>> = BTreeMap::new();
        for (idx, block) in body.iter().enumerate() {
            if !is_text_bearing(block) {
                continue;
            }
            let text = text_of(block);
            let (block_hits, ambiguities) = plan_block(text, registry);
            for collision in &ambiguities {
                let span = lift_span(source, block, collision.match_start, collision.match_end);
                diagnostics.push(ambiguous_match(span));
                had_ambiguous = true;
            }
            if !had_ambiguous && !block_hits.is_empty() {
                let block_steps: Vec<PlannedStep> = block_hits
                    .into_iter()
                    .map(|hit| PlannedStep {
                        text: crate::offsets::utf16_slice(text, hit.match_start, hit.match_end)
                            .to_string(),
                        match_span: lift_span(source, block, hit.match_start, hit.match_end),
                        param_spans: hit
                            .param_spans
                            .iter()
                            .map(|p| lift_span(source, block, p.start, p.end))
                            .collect(),
                        step_def: hit.step_def,
                        args: hit.args,
                        formats: hit.formats,
                        data_table: None,
                        doc_string: None,
                    })
                    .collect();
                steps_by_block.insert(idx, block_steps);
            }
        }

        // Header-bound table: iterate row by row.
        let bound = if had_ambiguous {
            None
        } else {
            detect_header_bound(body, &steps_by_block, source)
        };
        if let Some(bound) = bound {
            let header_binding = HeaderBinding {
                match_span: bound.step.match_span,
                param_spans: bound.header_spans.clone(),
                step_def: bound.step.step_def.clone(),
            };
            let header_cells = &bound.table.header.cells;
            for row in &bound.table.rows {
                let mut row_object = BTreeMap::new();
                for (i, header) in header_cells.iter().enumerate() {
                    row_object.insert(header.clone(), Value::from(cell_at(row, i)));
                }
                let mut row_args = bound.step.args.clone();
                row_args.push(Value::Map(row_object));
                let row_step = PlannedStep {
                    text: bound.step.text.clone(),
                    match_span: row.span,
                    param_spans: bound.step.param_spans.clone(),
                    step_def: bound.step.step_def.clone(),
                    args: row_args,
                    formats: bound.step.formats.clone(),
                    data_table: None,
                    doc_string: None,
                };
                let row_checks: Vec<RowCheck> = header_cells
                    .iter()
                    .enumerate()
                    .map(|(i, header)| {
                        RowCheck::new(header.clone(), cell_at(row, i), cell_span_at(row, i))
                    })
                    .collect();
                let mut nested_scope = ex.scope_stack.clone();
                nested_scope.push(bound.step.text.clone());
                examples.push(PlannedExample {
                    name: row.cells.join(" / "),
                    scope_stack: nested_scope,
                    span: row.span,
                    steps: vec![row_step],
                    header_binding: Some(HeaderBinding {
                        match_span: header_binding.match_span,
                        param_spans: header_binding.param_spans.clone(),
                        step_def: header_binding.step_def.clone(),
                    }),
                    row_checks: Some(row_checks),
                    expected_outcome: None,
                    expected_error_message: None,
                });
            }
            continue;
        }

        // An ```error fence anywhere marks the example expected-to-fail.
        let error_fence: Option<&Fence> = body.iter().find_map(|b| match b {
            Block::Fence(f) if f.info == "error" => Some(f),
            _ => None,
        });

        // Pass 2: table/fence immediately after a step-bearing block.
        let mut attachments: BTreeMap<usize, (Option<Table>, Option<Fence>)> = BTreeMap::new();
        for (idx, here) in body.iter().enumerate().skip(1) {
            match here {
                Block::Table(table) if steps_by_block.contains_key(&(idx - 1)) => {
                    attachments.entry(idx - 1).or_default().0 = Some(table.clone());
                }
                Block::Fence(fence)
                    if fence.info != "error" && steps_by_block.contains_key(&(idx - 1)) =>
                {
                    attachments.entry(idx - 1).or_default().1 = Some(fence.clone());
                }
                _ => {}
            }
        }

        // Pass 3: rebuild the final step list, applying attachments to the last
        // step of each block.
        let mut final_steps = Vec::new();
        for idx in 0..body.len() {
            let Some(steps_at_idx) = steps_by_block.get(&idx) else {
                continue;
            };
            let attach = attachments.get(&idx);
            let last = steps_at_idx.len() - 1;
            for (s, step) in steps_at_idx.iter().enumerate() {
                if s == last {
                    if let Some((data_table, doc_string)) = attach {
                        let mut with_attach = step.clone();
                        with_attach.data_table = data_table.clone();
                        with_attach.doc_string = doc_string.clone();
                        final_steps.push(with_attach);
                        continue;
                    }
                }
                final_steps.push(step.clone());
            }
        }

        let runnable_steps = if had_ambiguous {
            Vec::new()
        } else {
            final_steps.clone()
        };

        if let Some(fence) = error_fence {
            if runnable_steps.is_empty() {
                diagnostics.push(error_fence_without_step(fence.span));
            }
        }

        if final_steps.is_empty() && !had_ambiguous {
            continue;
        }

        let (expected_outcome, expected_error_message) = match error_fence {
            Some(fence) => {
                let trimmed = java_trim(&fence.body);
                let msg = if trimmed.is_empty() {
                    None
                } else {
                    Some(trimmed.to_string())
                };
                (Some("fail".to_string()), msg)
            }
            None => (None, None),
        };

        examples.push(PlannedExample {
            name: derive_example_name(body),
            scope_stack: ex.scope_stack.clone(),
            span: ex.span,
            steps: runnable_steps,
            header_binding: None,
            row_checks: None,
            expected_outcome,
            expected_error_message,
        });
    }

    ExecutionPlan {
        var_doc: doc.clone(),
        examples,
        diagnostics,
    }
}

struct Ambiguity {
    match_start: usize,
    match_end: usize,
}

fn plan_block(text: &str, registry: &Registry) -> (Vec<Hit>, Vec<Ambiguity>) {
    let mut all_steps = Vec::new();
    let mut all_ambiguities = Vec::new();
    for sentence in split_sentences(text) {
        let off = sentence.start_offset;
        let adjusted: Vec<Hit> = find_hits(&sentence.text, registry)
            .into_iter()
            .map(|h| {
                let param_spans = h
                    .param_spans
                    .iter()
                    .map(|p| ParamSpan {
                        start: p.start + off,
                        end: p.end + off,
                    })
                    .collect();
                Hit {
                    expression: h.expression,
                    step_def: h.step_def,
                    match_start: h.match_start + off,
                    match_end: h.match_end + off,
                    args: h.args,
                    param_spans,
                    formats: h.formats,
                }
            })
            .collect();
        match resolve_hits(adjusted) {
            ResolvedSteps::Ambiguous(collisions) => {
                for c in collisions {
                    all_ambiguities.push(Ambiguity {
                        match_start: c.match_start,
                        match_end: c.match_end,
                    });
                }
            }
            ResolvedSteps::Ok(steps) => {
                if !steps.is_empty() {
                    all_steps.extend(steps);
                }
            }
        }
    }
    (all_steps, all_ambiguities)
}

struct HeaderBoundResult {
    table: Table,
    step: PlannedStep,
    header_spans: Vec<Span>,
}

fn detect_header_bound(
    body: &[Block],
    steps_by_block: &BTreeMap<usize, Vec<PlannedStep>>,
    source: &str,
) -> Option<HeaderBoundResult> {
    for idx in 1..body.len() {
        let Block::Table(table) = &body[idx] else {
            continue;
        };
        let above = &body[idx - 1];
        if !is_text_bearing(above) {
            continue;
        }
        let Some(steps) = steps_by_block.get(&(idx - 1)) else {
            continue;
        };
        if steps.is_empty() {
            continue;
        }
        let above_text = text_of(above);
        let header_cells = &table.header.cells;
        let mut offsets = Vec::with_capacity(header_cells.len());
        let mut any_missing = false;
        for cell in header_cells {
            match word_offset(above_text, cell) {
                Some(o) => offsets.push(o),
                None => {
                    any_missing = true;
                    offsets.push(0);
                }
            }
        }
        if any_missing {
            continue;
        }
        let header_spans: Vec<Span> = header_cells
            .iter()
            .zip(&offsets)
            .map(|(cell, &o)| lift_span(source, above, o, o + utf16_len(cell)))
            .collect();
        return Some(HeaderBoundResult {
            table: table.clone(),
            step: steps.last().unwrap().clone(),
            header_spans,
        });
    }
    None
}

/// UTF-16 offset of `word` in `haystack` as a whole word (case-sensitive), or
/// `None`. Manual scan replacing Java's lookbehind/lookaround regex.
fn word_offset(haystack: &str, word: &str) -> Option<usize> {
    if word.is_empty() {
        return None;
    }
    let mut from = 0;
    while let Some(rel) = haystack[from..].find(word) {
        let at = from + rel;
        let before_ok = haystack[..at]
            .chars()
            .next_back()
            .is_none_or(|c| !is_word_char(c));
        let after = at + word.len();
        let after_ok = haystack[after..]
            .chars()
            .next()
            .is_none_or(|c| !is_word_char(c));
        if before_ok && after_ok {
            return Some(crate::offsets::utf16_index(haystack, at));
        }
        from = at + haystack[at..].chars().next().map_or(1, char::len_utf8);
    }
    None
}

fn is_word_char(c: char) -> bool {
    let mut buf = [0u8; 4];
    WORD_CHAR_RE.is_match(c.encode_utf8(&mut buf))
}

/// The example name: the primary block's text with whitespace collapsed and a
/// single trailing terminator stripped. Port of `deriveExampleName`.
pub(crate) fn derive_example_name(body: &[Block]) -> String {
    let Some(primary) = body.iter().find(|b| is_text_bearing(b)) else {
        return String::new();
    };
    let collapsed = WHITESPACE_RE.replace_all(text_of(primary), " ");
    let mut name = java_trim(&collapsed).to_string();
    if let Some(last) = name.chars().last() {
        if last == '.' || last == '!' || last == '?' {
            name.pop();
        }
    }
    name
}

fn is_text_bearing(block: &Block) -> bool {
    matches!(block, Block::Paragraph(_) | Block::ListItem(_) | Block::Blockquote(_))
}

fn text_of(block: &Block) -> &str {
    match block {
        Block::Paragraph(p) => &p.text,
        Block::ListItem(l) => &l.text,
        Block::Blockquote(b) => &b.text,
        _ => panic!("not a text-bearing block"),
    }
}

fn cell_at(row: &Row, i: usize) -> &str {
    row.cells.get(i).map_or("", |c| c.as_str())
}

fn cell_span_at(row: &Row, i: usize) -> Span {
    row.cell_spans.get(i).copied().unwrap_or(row.span)
}

fn segment_map_of(block: &Block) -> Option<&[SegmentOffset]> {
    match block {
        Block::Paragraph(p) => Some(&p.segment_map),
        Block::ListItem(l) => Some(&l.segment_map),
        Block::Blockquote(b) => Some(&b.segment_map),
        _ => None,
    }
}

fn lift_span(source: &str, block: &Block, block_start: usize, block_end: usize) -> Span {
    match segment_map_of(block) {
        Some(sm) => {
            let start = lift_segment_offset(sm, block_start);
            let end = lift_segment_offset(sm, block_end);
            Span::from_offsets(source, start, end)
        }
        None => block.span(),
    }
}

fn lift_segment_offset(segment_map: &[SegmentOffset], text_offset: usize) -> usize {
    let mut best = segment_map.first();
    for entry in segment_map {
        if entry.text_offset <= text_offset {
            best = Some(entry);
        }
    }
    let best = best.expect("empty segmentMap");
    best.source_offset + (text_offset - best.text_offset)
}