package validator

import (
	"sort"

	//nolint:staticcheck // bad, yeah
	. "github.com/vektah/gqlparser/v2/ast"
	"github.com/vektah/gqlparser/v2/gqlerror"
	"github.com/vektah/gqlparser/v2/validator/core"
	validatorrules "github.com/vektah/gqlparser/v2/validator/rules"
)

type (
	AddErrFunc  = core.AddErrFunc
	RuleFunc    = core.RuleFunc
	Rule        = core.Rule
	Events      = core.Events
	ErrorOption = core.ErrorOption
	Walker      = core.Walker
)

var (
	Message      = core.Message
	QuotedOrList = core.QuotedOrList
	OrList       = core.OrList
)

// Walk is an alias for core.Walk.
func Walk(schema *Schema, document *QueryDocument, observers *Events) {
	core.Walk(schema, document, observers)
}

var specifiedRules []Rule

func init() {
	// Initialize specifiedRules with default rules
	defaultRules := validatorrules.NewDefaultRules()
	for name, ruleFunc := range defaultRules.GetInner() {
		specifiedRules = append(specifiedRules, Rule{Name: name, RuleFunc: ruleFunc})
		// ensure initial default is in deterministic order
		sort.Sort(core.NameSorter(specifiedRules))
	}
}

// AddRule adds a rule to the rule set.
// ruleFunc is called once each time `Validate` is executed.
func AddRule(name string, ruleFunc RuleFunc) {
	specifiedRules = append(specifiedRules, Rule{Name: name, RuleFunc: ruleFunc})
}

// RemoveRule removes an existing rule from the rule set
// if one of the same name exists.
// The rule set is global, so it is not safe for concurrent changes.
func RemoveRule(name string) {
	var result []Rule //nolint:prealloc // using initialized with len(rules) produces a race condition
	for _, r := range specifiedRules {
		if r.Name == name {
			continue
		}
		result = append(result, r)
	}
	specifiedRules = result
}

// ReplaceRule replaces an existing rule from the rule set
// if one of the same name exists.
// If no match is found, it will add a new rule to the rule set.
// The rule set is global, so it is not safe for concurrent changes.
func ReplaceRule(name string, ruleFunc RuleFunc) {
	var found bool
	var result []Rule //nolint:prealloc // using initialized with len(rules) produces a race condition
	for _, r := range specifiedRules {
		if r.Name == name {
			found = true
			result = append(result, Rule{Name: name, RuleFunc: ruleFunc})
			continue
		}
		result = append(result, r)
	}
	if !found {
		specifiedRules = append(specifiedRules, Rule{Name: name, RuleFunc: ruleFunc})
		return
	}
	specifiedRules = result
}

// Deprecated: use ValidateWithRules instead.
func Validate(schema *Schema, doc *QueryDocument, rules ...Rule) gqlerror.List {
	if rules == nil {
		rules = specifiedRules
	}

	var errs gqlerror.List
	if schema == nil {
		errs = append(errs, gqlerror.Errorf("cannot validate as Schema is nil"))
	}
	if doc == nil {
		errs = append(errs, gqlerror.Errorf("cannot validate as QueryDocument is nil"))
	}
	if len(errs) > 0 {
		return errs
	}
	observers := &core.Events{}
	for i := range rules {
		rule := rules[i]
		rule.RuleFunc(observers, func(options ...ErrorOption) {
			err := &gqlerror.Error{
				Rule: rule.Name,
			}
			for _, o := range options {
				o(err)
			}
			errs = append(errs, err)
		})
	}

	Walk(schema, doc, observers)
	return errs
}

func ValidateWithRules(
	schema *Schema,
	doc *QueryDocument,
	rules *validatorrules.Rules,
) gqlerror.List {
	if rules == nil {
		rules = validatorrules.NewDefaultRules()
	}

	var errs gqlerror.List
	if schema == nil {
		errs = append(errs, gqlerror.Errorf("cannot validate as Schema is nil"))
	}
	if doc == nil {
		errs = append(errs, gqlerror.Errorf("cannot validate as QueryDocument is nil"))
	}
	if len(errs) > 0 {
		return errs
	}
	observers := &core.Events{}

	var currentRules []Rule //nolint:prealloc // would require extra local refs for len
	for name, ruleFunc := range rules.GetInner() {
		currentRules = append(currentRules, Rule{Name: name, RuleFunc: ruleFunc})
		// ensure deterministic order evaluation
		sort.Sort(core.NameSorter(currentRules))
	}

	for _, currentRule := range currentRules {
		currentRule.RuleFunc(observers, func(options ...ErrorOption) {
			err := &gqlerror.Error{
				Rule: currentRule.Name,
			}
			for _, o := range options {
				o(err)
			}
			errs = append(errs, err)
		})
	}

	Walk(schema, doc, observers)
	return errs
}
