feat(import): add table import wizard

apps/desktop/src/lib/table/tableImport.ts

@@ -1,5 +1,28 @@
 export const IMPORT_SKIP_TARGET = "";
 
+export interface ImportColumnMappingLike {
+  sourceColumn: string;
+  targetColumn: string;
+}
+
+export interface ImportMappingValidationResult {
+  valid: boolean;
+  errors: string[];
+  duplicateTargets: string[];
+}
+
+export interface ImportTargetColumnLike {
+  name: string;
+  is_nullable?: boolean;
+  column_default?: string | null;
+  extra?: string | null;
+  is_primary_key?: boolean;
+}
+
+export type TableImportWizardStep = "source" | "options" | "mapping" | "review" | "execution";
+
+export const TABLE_IMPORT_WIZARD_STEPS: TableImportWizardStep[] = ["source", "options", "mapping", "review", "execution"];
+
 export function normalizeImportColumnName(name: string): string {
   return name.trim().toLowerCase().replace(/[_-]+/g, " ").replace(/\s+/g, " ");
 }
@@ -10,3 +33,51 @@ export function autoMapImportColumns(sourceColumns: string[], targetColumns: str
 
   return Object.fromEntries(sourceColumns.map((source) => [source, exactTargets.get(source) ?? normalizedTargets.get(normalizeImportColumnName(source)) ?? IMPORT_SKIP_TARGET]));
 }
+
+export function validateImportMappings(mappings: ImportColumnMappingLike[]): ImportMappingValidationResult {
+  const activeMappings = mappings.filter((mapping) => mapping.targetColumn.trim());
+  const errors: string[] = [];
+  const duplicateTargets: string[] = [];
+  if (activeMappings.length === 0) {
+    errors.push("No columns mapped for import");
+  }
+
+  const seen = new Set<string>();
+  for (const mapping of activeMappings) {
+    const key = mapping.targetColumn.trim().toLowerCase();
+    if (seen.has(key) && !duplicateTargets.includes(mapping.targetColumn)) {
+      duplicateTargets.push(mapping.targetColumn);
+    }
+    seen.add(key);
+  }
+  if (duplicateTargets.length) {
+    errors.push(`Target column mapped more than once: ${duplicateTargets.join(", ")}`);
+  }
+
+  return { valid: errors.length === 0, errors, duplicateTargets };
+}
+
+export function requiredImportTargetColumns(columns: ImportTargetColumnLike[], mappedTargetColumns: string[]): string[] {
+  const mapped = new Set(mappedTargetColumns.map((column) => column.toLowerCase()));
+  return columns
+    .filter((column) => !mapped.has(column.name.toLowerCase()))
+    .filter(
+      (column) =>
+        column.is_nullable === false &&
+        !column.column_default &&
+        !String(column.extra || "")
+          .toLowerCase()
+          .includes("auto"),
+    )
+    .map((column) => column.name);
+}
+
+export function nextTableImportWizardStep(step: TableImportWizardStep): TableImportWizardStep {
+  const index = TABLE_IMPORT_WIZARD_STEPS.indexOf(step);
+  return TABLE_IMPORT_WIZARD_STEPS[Math.min(TABLE_IMPORT_WIZARD_STEPS.length - 1, Math.max(0, index) + 1)];
+}
+
+export function previousTableImportWizardStep(step: TableImportWizardStep): TableImportWizardStep {
+  const index = TABLE_IMPORT_WIZARD_STEPS.indexOf(step);
+  return TABLE_IMPORT_WIZARD_STEPS[Math.max(0, index - 1)];
+}