/**
 * Human-readable reporter output.
 *
 * Turns diagnostics, traces, and shrink results into plain text
 * suitable for terminal reading.
 */

import type { Diagnostic } from './diagnostics.js';
import type { TraceEvent } from './traces.js';
import type { ShrinkResult } from './shrink.js';

/**
 * Options for human formatting.
 * Injected so callers control colors, verbosity, etc.
 */
export interface HumanFormatOptions {
  // show trace events after each diagnostic
  showTraces?: boolean;
  // show shrink summary when available
  showShrink?: boolean;
  // max related facts to print
  maxRelated?: number;
}

/**
 * Render a list of diagnostics into a human-readable string.
 */
export function renderHumanReport(
  diagnostics: Diagnostic[],
  traces: readonly TraceEvent[],
  shrinkResults: Map<string, ShrinkResult>,
  opts: HumanFormatOptions = {},
): string {
  const lines: string[] = [];

  for (const d of diagnostics) {
    lines.push(renderDiagnostic(d, opts));

    if (opts.showShrink && d.clauseId && shrinkResults.has(d.clauseId)) {
      const shrink = shrinkResults.get(d.clauseId)!;
      lines.push(renderShrink(shrink));
    }

    if (opts.showTraces && d.traceRef) {
      const relevant = traces.filter(
        (t) => t.traceEventId === d.traceRef || t.refs.diagnosticId === d.diagnosticId,
      );
      if (relevant.length > 0) {
        lines.push('  trace:');
        for (const t of relevant) {
          lines.push(`    ${t.phase} at ${t.at}`);
        }
      }
    }
  }

  return lines.join('\n');
}

/**
 * Render a single diagnostic in human form.
 */
export function renderDiagnostic(
  d: Diagnostic,
  opts: HumanFormatOptions = {},
): string {
  const lines: string[] = [];
  const prefix = d.severity === 'error' ? '✖' : d.severity === 'warning' ? '⚠' : 'ℹ';
  lines.push(`${prefix} ${d.message}`);
  lines.push(`  ${d.code}`);

  if (d.position) {
    lines.push(
      `  at line ${d.position.start.line}, column ${d.position.start.column}`,
    );
  }

  const maxRelated = opts.maxRelated ?? 5;
  if (d.related.length > 0) {
    lines.push('  related:');
    for (const r of d.related.slice(0, maxRelated)) {
      lines.push(`    • ${r.message}`);
    }
    if (d.related.length > maxRelated) {
      lines.push(`    … and ${d.related.length - maxRelated} more`);
    }
  }

  if (d.fixHints.length > 0) {
    lines.push('  hints:');
    for (const h of d.fixHints) {
      lines.push(`    → ${h}`);
    }
  }

  if (d.suggestedFix) {
    lines.push('  suggested fix:');
    lines.push(`    action: ${d.suggestedFix.action}`);
    lines.push(`    target: ${d.suggestedFix.target}`);
    lines.push(`    value: ${d.suggestedFix.value}`);
    lines.push(`    rationale: ${d.suggestedFix.rationale}`);
  }

  return lines.join('\n');
}

/**
 * Render a shrink result summary.
 */
export function renderShrink(result: ShrinkResult): string {
  const lines: string[] = [];
  lines.push('  shrink:');
  if (result.reduced) {
    lines.push(`    reduced across: ${result.axes.join(', ')}`);
    lines.push(`    steps: ${result.steps}`);
  } else {
    lines.push('    no reduction possible');
  }
  return lines.join('\n');
}