specsync 2.1.1

use crate::exports::get_exported_symbols;
use crate::parser::{get_missing_sections, get_spec_symbols, parse_frontmatter};
use crate::types::SpecSyncConfig;
use std::collections::HashSet;
use std::fs;
use std::path::Path;

/// Quality score for a single spec file.
#[derive(Debug)]
pub struct SpecScore {
    pub spec_path: String,
    /// Frontmatter completeness (0-20).
    pub frontmatter_score: u32,
    /// Required sections present (0-20).
    pub sections_score: u32,
    /// API documentation coverage (0-20).
    pub api_score: u32,
    /// Content depth — sections have real content, not just TODOs (0-20).
    pub depth_score: u32,
    /// Freshness — files exist, no stale references (0-20).
    pub freshness_score: u32,
    /// Overall score (0-100).
    pub total: u32,
    /// Letter grade.
    pub grade: &'static str,
    /// Actionable suggestions for improvement.
    pub suggestions: Vec<String>,
}

/// Score a single spec file.
pub fn score_spec(spec_path: &Path, root: &Path, config: &SpecSyncConfig) -> SpecScore {
    let rel_path = spec_path
        .strip_prefix(root)
        .unwrap_or(spec_path)
        .to_string_lossy()
        .to_string();

    let mut score = SpecScore {
        spec_path: rel_path,
        frontmatter_score: 0,
        sections_score: 0,
        api_score: 0,
        depth_score: 0,
        freshness_score: 0,
        total: 0,
        grade: "F",
        suggestions: Vec::new(),
    };

    let content = match fs::read_to_string(spec_path) {
        Ok(c) => c.replace("\r\n", "\n"),
        Err(_) => {
            score.suggestions.push("Cannot read spec file".to_string());
            return score;
        }
    };

    let parsed = match parse_frontmatter(&content) {
        Some(p) => p,
        None => {
            score
                .suggestions
                .push("Add YAML frontmatter with --- delimiters".to_string());
            return score;
        }
    };

    let fm = &parsed.frontmatter;
    let body = &parsed.body;

    // ─── Frontmatter (0-20) ──────────────────────────────────────────
    let mut fm_points = 0u32;
    if fm.module.is_some() {
        fm_points += 5;
    } else {
        score
            .suggestions
            .push("Add `module:` field to frontmatter".to_string());
    }
    if fm.version.is_some() {
        fm_points += 5;
    } else {
        score
            .suggestions
            .push("Add `version:` field to frontmatter".to_string());
    }
    if fm.status.is_some() {
        fm_points += 4;
    } else {
        score
            .suggestions
            .push("Add `status:` field to frontmatter".to_string());
    }
    if !fm.files.is_empty() {
        fm_points += 6;
    } else {
        score
            .suggestions
            .push("Add `files:` list linking spec to source files".to_string());
    }
    score.frontmatter_score = fm_points;

    // ─── Sections (0-20) ─────────────────────────────────────────────
    let missing = get_missing_sections(body, &config.required_sections);
    let present = config.required_sections.len() - missing.len();
    let total_sections = config.required_sections.len();
    score.sections_score = if total_sections == 0 {
        20
    } else {
        ((present as f64 / total_sections as f64) * 20.0).round() as u32
    };
    if !missing.is_empty() {
        let names = missing
            .iter()
            .take(3)
            .cloned()
            .collect::<Vec<_>>()
            .join(", ");
        let suffix = if missing.len() > 3 {
            format!(" (+{} more)", missing.len() - 3)
        } else {
            String::new()
        };
        score
            .suggestions
            .push(format!("Add missing sections: {names}{suffix}"));
    }

    // ─── API Coverage (0-20) ─────────────────────────────────────────
    if !fm.files.is_empty() {
        let mut all_exports: Vec<String> = Vec::new();
        for file in &fm.files {
            let full_path = root.join(file);
            all_exports.extend(get_exported_symbols(&full_path));
        }
        let mut seen = HashSet::new();
        all_exports.retain(|s| seen.insert(s.clone()));

        let spec_symbols = get_spec_symbols(body);
        let export_set: HashSet<&str> = all_exports.iter().map(|s| s.as_str()).collect();

        let documented = spec_symbols
            .iter()
            .filter(|s| export_set.contains(s.as_str()))
            .count();

        if all_exports.is_empty() {
            score.api_score = 20; // No exports to document
        } else {
            score.api_score =
                ((documented as f64 / all_exports.len() as f64) * 20.0).round() as u32;
            let undocumented = all_exports.len() - documented;
            if undocumented > 0 {
                score.suggestions.push(format!(
                    "Document {undocumented} undocumented export(s) in ## Public API"
                ));
            }
        }
    } else {
        score.api_score = 0;
    }

    // ─── Content Depth (0-20) ────────────────────────────────────────
    let mut depth_points = 0u32;
    let todo_count = count_placeholder_todos(body);
    let placeholder_count = body.matches("<!-- ").count();

    // Check each required section has meaningful content
    let sections_with_content = count_sections_with_content(body, &config.required_sections);
    let content_ratio = if config.required_sections.is_empty() {
        1.0
    } else {
        sections_with_content as f64 / config.required_sections.len() as f64
    };
    depth_points += (content_ratio * 14.0).round() as u32;

    // Penalize TODOs
    if todo_count == 0 && placeholder_count == 0 {
        depth_points += 6;
    } else if todo_count <= 2 {
        depth_points += 3;
    } else {
        score.suggestions.push(format!(
            "Fill in {todo_count} TODO placeholder(s) with real content"
        ));
    }
    score.depth_score = depth_points.min(20);

    // ─── Freshness (0-20) ────────────────────────────────────────────
    let mut fresh_points = 20u32;
    let mut stale_files = 0u32;
    for file in &fm.files {
        if !root.join(file).exists() {
            stale_files += 1;
        }
    }
    if stale_files > 0 {
        let penalty = (stale_files * 5).min(15);
        fresh_points = fresh_points.saturating_sub(penalty);
        score.suggestions.push(format!(
            "Fix {stale_files} stale file reference(s) in frontmatter"
        ));
    }

    // Check depends_on references
    let mut stale_deps = 0u32;
    for dep in &fm.depends_on {
        if !root.join(dep).exists() {
            stale_deps += 1;
        }
    }
    if stale_deps > 0 {
        fresh_points = fresh_points.saturating_sub(stale_deps * 3);
        score.suggestions.push(format!(
            "Fix {stale_deps} stale dependency reference(s) in frontmatter"
        ));
    }
    score.freshness_score = fresh_points;

    // ─── Total & Grade ───────────────────────────────────────────────
    score.total = score.frontmatter_score
        + score.sections_score
        + score.api_score
        + score.depth_score
        + score.freshness_score;

    score.grade = match score.total {
        90..=100 => "A",
        80..=89 => "B",
        70..=79 => "C",
        60..=69 => "D",
        _ => "F",
    };

    score
}

/// Count TODO/todo occurrences that are actual placeholders, ignoring:
/// - Occurrences inside fenced code blocks (``` ... ```)
/// - Compound terms like "TODO-marker", "TODO_detection", "TODOs"
/// - Descriptive prose where TODO is used as a concept (e.g., "TODO comments", "detect TODO")
fn count_placeholder_todos(body: &str) -> usize {
    use regex::Regex;

    // Strip fenced code blocks
    let code_block_re = Regex::new(r"(?s)```[^\n]*\n.*?```").unwrap();
    let stripped = code_block_re.replace_all(body, "");

    // Placeholder pattern: line is just "TODO"/"todo", or starts with "TODO:"
    let todo_line_re = Regex::new(r"(?i)^TODO\s*(:.*)?$").unwrap();

    let mut count = 0;
    for line in stripped.lines() {
        let trimmed = line
            .trim()
            .trim_start_matches("- ")
            .trim_start_matches("* ");
        if todo_line_re.is_match(trimmed) {
            count += 1;
        }
    }
    count
}

/// Count how many required sections have meaningful content (more than just a heading).
fn count_sections_with_content(body: &str, required_sections: &[String]) -> usize {
    let mut count = 0;
    for section in required_sections {
        let header = format!("## {section}");
        if let Some(start) = body.find(&header) {
            let after = start + header.len();
            // Find end of this section (next ## or end of body)
            let rest = &body[after..];
            let end = rest.find("\n## ").unwrap_or(rest.len());
            let section_body = rest[..end].trim();

            // Has content beyond placeholders?
            let meaningful = section_body
                .lines()
                .filter(|l| {
                    let t = l.trim();
                    !t.is_empty()
                        && !t.starts_with("<!--")
                        && !t.starts_with("|--")
                        && !t.starts_with("| -")
                        && t != "TODO"
                        && !t.contains("<!-- TODO")
                })
                .count();

            if meaningful >= 1 {
                count += 1;
            }
        }
    }
    count
}

/// Aggregate scores for a project.
pub struct ProjectScore {
    pub spec_scores: Vec<SpecScore>,
    pub average_score: f64,
    pub grade: &'static str,
    pub total_specs: usize,
    pub grade_distribution: [usize; 5], // A, B, C, D, F
}

pub fn compute_project_score(spec_scores: Vec<SpecScore>) -> ProjectScore {
    let total_specs = spec_scores.len();
    let average_score = if total_specs == 0 {
        0.0
    } else {
        spec_scores.iter().map(|s| s.total as f64).sum::<f64>() / total_specs as f64
    };

    let mut distribution = [0usize; 5];
    for s in &spec_scores {
        match s.grade {
            "A" => distribution[0] += 1,
            "B" => distribution[1] += 1,
            "C" => distribution[2] += 1,
            "D" => distribution[3] += 1,
            _ => distribution[4] += 1,
        }
    }

    let grade = match average_score.round() as u32 {
        90..=100 => "A",
        80..=89 => "B",
        70..=79 => "C",
        60..=69 => "D",
        _ => "F",
    };

    ProjectScore {
        spec_scores,
        average_score,
        grade,
        total_specs,
        grade_distribution: distribution,
    }
}