package main

import (
	"encoding/csv"
	"fmt"
	"strings"

	specs "github.com/opencontainers/runtime-spec/specs-go"
)

// parseMountFlag parses a mount string in the form "type=foo,source=/path,destination=/target,options=rbind:rw"
func parseMountFlag(m string) (specs.Mount, error) {
	mount := specs.Mount{}
	r := csv.NewReader(strings.NewReader(m))

	fields, err := r.Read()
	if err != nil {
		return mount, err
	}

	for _, field := range fields {
		v := strings.Split(field, "=")
		if len(v) != 2 {
			return mount, fmt.Errorf("invalid mount specification: expected key=val")
		}

		key := v[0]
		val := v[1]
		switch key {
		case "type":
			mount.Type = val
		case "source", "src":
			mount.Source = val
		case "destination", "dst":
			mount.Destination = val
		case "options":
			mount.Options = strings.Split(val, ":")
		default:
			return mount, fmt.Errorf("mount option %q not supported", key)
		}
	}

	return mount, nil
}

// replaceOrAppendEnvValues returns the defaults with the overrides either
// replaced by env key or appended to the list
func replaceOrAppendEnvValues(defaults, overrides []string) []string {
	cache := make(map[string]int, len(defaults))
	for i, e := range defaults {
		parts := strings.SplitN(e, "=", 2)
		cache[parts[0]] = i
	}

	for _, value := range overrides {
		// Values w/o = means they want this env to be removed/unset.
		if !strings.Contains(value, "=") {
			if i, exists := cache[value]; exists {
				defaults[i] = "" // Used to indicate it should be removed
			}
			continue
		}

		// Just do a normal set/update
		parts := strings.SplitN(value, "=", 2)
		if i, exists := cache[parts[0]]; exists {
			defaults[i] = value
		} else {
			defaults = append(defaults, value)
		}
	}

	// Now remove all entries that we want to "unset"
	for i := 0; i < len(defaults); i++ {
		if defaults[i] == "" {
			defaults = append(defaults[:i], defaults[i+1:]...)
			i--
		}
	}

	return defaults
}