/**
 * migration-name.ts — Pure naming formatter.
 *
 * Convention ported from the global /efcore agents (without MCP):
 *   {contextPrefix}_v{version_underscore}_{seq3}_{PascalCaseDescription}
 *
 * Examples:
 *   core_v0_4_0_007_AddEmployeeAvatar
 *   ext_v1_0_0_003_CreateOrders
 *   studio_v1_0_0_005_AddBugWorkflow
 *
 * - `contextPrefix` is lowercased and collapsed (ExtensionsDbContext → ext,
 *   CoreDbContext → core, StudioDbContext → studio).
 * - Description is PascalCase with only [A-Za-z0-9] characters. Empty input
 *   throws — the caller must validate.
 */
import { normalizeVersionForName } from './parse-csproj-version.js';

export interface MigrationNameInput {
  contextName: string;
  version: string;
  sequence: number;
  description: string;
}

export function contextPrefix(contextName: string): string {
  const stripped = contextName.replace(/DbContext$/i, '').replace(/Context$/i, '');
  const lower = stripped.toLowerCase();
  if (lower === 'extensions') return 'ext';
  if (lower === 'extension') return 'ext';
  return lower || 'db';
}

export function toPascalCase(input: string): string {
  const parts = input
    .replace(/[^A-Za-z0-9\s_-]/g, ' ')
    .split(/[\s_-]+/)
    .filter(Boolean);
  if (parts.length === 0) return '';
  return parts.map((p) => p.charAt(0).toUpperCase() + p.slice(1)).join('');
}

export function padSequence(n: number): string {
  return String(Math.max(0, Math.floor(n))).padStart(3, '0');
}

export function buildMigrationName(input: MigrationNameInput): string {
  const desc = toPascalCase(input.description);
  if (!desc) {
    throw new Error('description must contain at least one alphanumeric character');
  }
  const prefix = contextPrefix(input.contextName);
  const vPart = normalizeVersionForName(input.version);
  const seq = padSequence(input.sequence);
  return `${prefix}_v${vPart}_${seq}_${desc}`;
}