import { z } from "zod";
import type { ScriptConfig, VariableConfig } from "../config/schema";

function fieldSchema(variable: VariableConfig): z.ZodTypeAny {
  let field: z.ZodTypeAny;

  switch (variable.type) {
    case "string": {
      let s = z.string();
      // `required` alone has to reject "" even when the author didn't set an explicit
      // minLength - otherwise an empty string satisfies a bare z.string() and the run starts
      // with a "required" field effectively unset.
      const minLength =
        variable.minLength ?? (variable.required ? 1 : undefined);
      if (minLength !== undefined) s = s.min(minLength);
      if (variable.maxLength !== undefined) s = s.max(variable.maxLength);
      if (variable.pattern) s = s.regex(new RegExp(variable.pattern));
      field = s;
      break;
    }
    case "number": {
      let n = z.number();
      if (variable.min !== undefined) n = n.min(variable.min);
      if (variable.max !== undefined) n = n.max(variable.max);
      field = n;
      break;
    }
    case "boolean":
      field = z.boolean();
      break;
    case "enum":
      field = z.enum(variable.choices as [string, ...string[]]);
      break;
    case "multiselect": {
      let arr = z.array(z.enum(variable.choices as [string, ...string[]]));
      if (variable.required) arr = arr.min(1);
      field = arr;
      break;
    }
  }

  if (!variable.required) {
    field = field.optional().or(z.literal(""));
  }

  return field;
}

/** Builds one Zod object schema from a list of variable definitions - the single source of truth
 * imported by both the client form resolver and the server-side run-creation handler. */
export function buildVariableSchemaFromList(
  variables: readonly VariableConfig[],
) {
  const shape: Record<string, z.ZodTypeAny> = {};
  for (const variable of variables) {
    shape[variable.name] = fieldSchema(variable);
  }
  return z.object(shape);
}

export function buildVariableSchema(script: ScriptConfig) {
  return buildVariableSchemaFromList(script.variables);
}

export type VariableValues = Record<string, unknown>;