package graphql

import (
	"context"
	"reflect"
)

type PaginatedQuery[ResultType any, Params any] struct {
	c               *Client
	gqltype         string
	containerLayers []string

	additionalPayloadParams map[string]interface{}
	additionalQueryParams   map[string]interface{}
}

func NewPaginatedQuery[ResultType any, Params any](
	c *Client,
	gqlType string,
	containerLayers []string,
) *PaginatedQuery[ResultType, Params] {
	return &PaginatedQuery[ResultType, Params]{
		c:                       c,
		gqltype:                 gqlType,
		containerLayers:         containerLayers,
		additionalPayloadParams: make(map[string]interface{}),
		additionalQueryParams:   make(map[string]interface{}),
	}
}

func (pq *PaginatedQuery[ResultType, Params]) WithPayloadParam(
	name string,
	value interface{},
) *PaginatedQuery[ResultType, Params] {
	pq.additionalPayloadParams[name] = value
	return pq
}

func (pq *PaginatedQuery[ResultType, Params]) WithQueryParam(
	name string,
	value interface{},
) *PaginatedQuery[ResultType, Params] {
	pq.additionalQueryParams[name] = value
	return pq
}

type PaginatedQueryGetOptions struct {
	Limit int
}

func WithPaginatedQueryLimit(limit int) func(options *PaginatedQueryGetOptions) {
	return func(options *PaginatedQueryGetOptions) {
		options.Limit = limit
	}
}

func (pq *PaginatedQuery[ResultType, Params]) Get(
	ctx context.Context,
	params Params,
	options ...func(options *PaginatedQueryGetOptions),
) ([]ResultType, error) {
	opts := &PaginatedQueryGetOptions{
		Limit: 0,
	}
	for _, opt := range options {
		opt(opts)
	}
	var res []ResultType
	after := ""
	var noop ResultType
	pageSize := (pq.c.MaxComplexity() - 9) / (GetComplexity(reflect.TypeOf(noop)) + 1)
	for {
		page, pi, err := pq.getPage(ctx, params, after, pageSize)
		if err != nil {
			return nil, err
		}
		for _, item := range page {
			res = append(res, item)
			if opts.Limit > 0 && len(res) >= opts.Limit {
				return res, nil
			}
		}
		if !pi.HasNextPage {
			break
		}
		after = pi.EndCursor
	}
	return res, nil
}

type PageInfo struct {
	EndCursor       string `graphql:"endCursor"`
	HasNextPage     bool   `graphql:"hasNextPage"`
	HasPreviousPage bool   `graphql:"hasPreviousPage"`
	StartCursor     string `graphql:"startCursor"`
}

func (pq *PaginatedQuery[ResultType, Params]) getPage(
	ctx context.Context,
	params Params,
	after string,
	first int,
) ([]ResultType, PageInfo, error) {
	type PageResult struct {
		Nodes    []ResultType `graphql:"nodes"`
		PageInfo PageInfo     `graphql:"pageInfo"`
	}
	q := NewQuery[PageResult, Params](pq.c, pq.gqltype, pq.containerLayers).
		WithPayloadParam("first", first)
	if after != "" {
		q = q.WithPayloadParam("after", after)
	}
	for k, v := range pq.additionalPayloadParams {
		q.WithPayloadParam(k, v)
	}
	for k, v := range pq.additionalQueryParams {
		q.WithQueryParam(k, v)
	}
	res, err := q.Get(ctx, params)
	if err != nil {
		return nil, PageInfo{}, err
	}
	return res.Nodes, res.PageInfo, nil
}

func GetComplexity(t reflect.Type) int {
	var checkStruct func(t reflect.Type, complexity *int)
	checkStruct = func(t reflect.Type, complexity *int) {
		if t.Kind() != reflect.Struct {
			return
		}
		for i := 0; i < t.NumField(); i++ {
			field := t.Field(i)
			if field.Type.Kind() == reflect.Struct {
				*complexity++
				tag := field.Tag.Get("graphql")
				if len(tag) > 6 && tag[:6] == "... on" {
					*complexity--
				}
				checkStruct(field.Type, complexity)
				continue
			}
			if field.Type.Kind() == reflect.Slice {
				*complexity++
				tmpcomplexity := 0
				checkStruct(field.Type.Elem(), &tmpcomplexity)
				*complexity += tmpcomplexity * 10
				continue
			}
			*complexity++
		}
	}
	complexity := 0
	checkStruct(t, &complexity)
	return complexity
}