package main

import (
	"fmt"
	"tildegit.org/sloum/filtress/parser"
)

func (f *filter) update(change parser.Expression, vars map[string]int) {
	opand := change.Opperand
	if change.Variable != "" {
		if val, ok := vars[change.Variable]; ok {
			opand = val
		} else {
			panic(fmt.Sprintf("Runtime error: Encountered unknown variable %q", val))
		}
	}

	switch change.Opperator {
	case '+':
		f.val += opand
	case '-':
		f.val -= opand
	case '*':
		f.val *= opand
	case '/':
		if opand == 0 {
			f.val = 1
		} else {
			f.val /= opand
		}
	case '=':
		f.val = opand
	}
	if f.val > f.max {
		f.val %= f.max
	}
	if f.val < f.min {
		f.val = f.max - f.val%f.max
	}
}

func (p *point) update(change []parser.Expression, vars map[string]int) {
	var totalX, totalY, val, opand, max int
	var target *int

	for i, e := range change {
		if i == 0 {
			target = &totalX
			val = p.x
			max = p.maxX
		} else if i == 1 {
			target = &totalY
			val = p.y
			max = p.maxY
		} else {
			break
		}

		if e.Variable != "" {
			if val, ok := vars[e.Variable]; ok {
				opand = val
			} else {
				panic(fmt.Sprintf("Runtime error: Encountered unknown variable %q", val))
			}
		} else {
			opand = e.Opperand
		}

		switch e.Opperator {
		case '+':
			*target = val + opand
		case '-':
			*target = val - opand
		case '*':
			*target = val * opand
		case '/':
			if opand == 0 {
				*target = 1
			} else {
				*target = val / opand
			}
		case '=':
			*target = opand
		}

		if *target > max {
			*target %= max
		}

		if *target < 0 {
			*target = max - *target%max
		}
	}
	p.x = totalX
	p.y = totalY
}