package nomino

import (
	"fmt"
	"strconv"
)

type incConf struct {
	start int
	step  int
	cb    func(int) string
}

// IncrementalOption sets an option for the [Incremental] [Generator].
type IncrementalOption func(c *incConf)

// Incremental generates a name that is a series of integers.
// By default it begins at 0 and increments by 1 each time.
func Incremental(opts ...IncrementalOption) Generator {
	c := incConf{step: 1, cb: strconv.Itoa}
	for _, opt := range opts {
		opt(&c)
	}

	next := c.start
	return func(*Config) (string, error) {
		out := c.cb(next)
		next += c.step
		return out, nil
	}
}

// IncrementalStart sets the starting integer for [Incremental].
func IncrementalStart(start int) IncrementalOption {
	return func(c *incConf) {
		c.start = start
	}
}

// IncrementalStepsets the step by which [Incremental] increases with each invocation.
func IncrementalStep(step int) IncrementalOption {
	return func(c *incConf) {
		c.step = step
	}
}

// IncrementalFormatsets the format for the number generated by [Incremental].
// It will be formatted with Printf. This is mostly likely useful with a format like "%02d".
func IncrementalFormat(format string) IncrementalOption {
	return func(c *incConf) {
		c.cb = func(i int) string {
			return fmt.Sprintf(format, i)
		}
	}
}