package sravni

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"log/slog"
	"strings"

	"git.loyso.art/frx/kurious/internal/domain"

	"github.com/go-resty/resty/v2"
	"golang.org/x/net/html"
	"golang.org/x/net/html/atom"
)

const (
	baseURL = "https://www.sravni.ru/kursy"
)

func NewClient(log *slog.Logger, debug bool) *client {
	return &client{
		log: log.With(slog.String("client", "sravni")),
		http: resty.New().
			SetBaseURL(baseURL).
			SetDebug(debug),
	}
}

type client struct {
	log  *slog.Logger
	http *resty.Client
}

type MetaInfoRuntimeConfig struct {
	BrandingURL      string `json:"brandingUrl"`
	Release          string `json:"release"`
	Environment      string `json:"environment"`
	Gateway          string `json:"gatewayUrl"`
	APIGatewayURL    string `json:"apiGatewayUrl"`
	EducationURL     string `json:"educationUrl"`
	PhoneVerifierURL string `json:"phoneVerifierUrl"`
	WebPath          string `json:"webPath"`
	ServiceName      string `json:"serviceName"`
	OrgnazationURL   string `json:"organizationsUrl"`
}

type MetaInfoReduxState struct {
	Categories struct {
		Data map[string]int `json:"data"`
	} `json:"categories"`
}

type MetaInfoProps struct {
	InitialReduxState MetaInfoReduxState `json:"initialReduxState"`
}

type MetaInfo struct {
	Page          string                `json:"page"`
	Query         map[string]string     `json:"query"`
	BuildID       string                `json:"buildId"`
	RuntimeConfig MetaInfoRuntimeConfig `json:"runtimeConfig"`
	Props         MetaInfoProps         `json:"props"`
}

func (c *client) GetMetaInfo(ctx context.Context) (*MetaInfo, error) {
	ctxLogger := restyCtxLogger{
		ctx: ctx,
		log: c.log,
	}

	req := c.http.R().
		SetContext(ctx).
		SetLogger(ctxLogger).
		EnableTrace()

	resp, err := req.Get("/")
	if err != nil {
		return nil, fmt.Errorf("getting request: %w", err)
	}

	if resp.IsError() {
		c.log.ErrorContext(ctx, "unable to proceed request", slog.String("body", string(resp.Body())))
		return nil, fmt.Errorf("got %d, but expected success: %w", resp.StatusCode(), domain.UnexpectedStatusError)
	}

	traceInfo := resp.Request.TraceInfo()
	c.log.InfoContext(ctx, "request proceeded", slog.Any("trace", traceInfo))

	r := bytes.NewReader(resp.Body())
	nodes, err := html.Parse(r)
	if err != nil {
		return nil, fmt.Errorf("parsing html body: %w", err)
	}

	c.log.InfoContext(ctx, "inspecting node", slog.Any("node", nodes))

	htmlNode := func() *html.Node {
		for child := nodes.FirstChild; child != nil; child = child.NextSibling {
			c.log.InfoContext(ctx, "inspecting node", slog.Any("node", child))
			if child.Type == html.ElementNode {
				return child
			}
		}

		return nil
	}()
	if htmlNode == nil {
		c.log.WarnContext(ctx, "no html node found")
		return nil, nil
	}

	var bodyNode *html.Node
	for child := htmlNode.FirstChild; child != nil; child = child.NextSibling {
		c.log.InfoContext(ctx, "inspecting html node", slog.Any("node", child))
		if child.DataAtom == atom.Body {
			c.log.InfoContext(ctx, "found body node")
			bodyNode = child
			break
		}
	}

	var nextData *html.Node
	for child := bodyNode.FirstChild; child != nil; child = child.NextSibling {
		c.log.InfoContext(ctx, "inspecting body node", slog.Any("node", child))
		if child.DataAtom == atom.Script {
			c.log.InfoContext(ctx, "found script node")
			for _, attr := range child.Attr {
				if attr.Key == "id" && attr.Val == "__NEXT_DATA__" {
					c.log.InfoContext(ctx, "found metadata container")
					nextData = child.FirstChild
					break
				}
			}
		}
	}

	if nextData == nil {
		c.log.WarnContext(ctx, "no metadata container found")
		return nil, nil
	}

	var out MetaInfo
	dataReader := strings.NewReader(nextData.Data)
	err = json.NewDecoder(dataReader).Decode(&out)
	if err != nil {
		return nil, fmt.Errorf("unmarshalling data: %w", err)
	}

	return &out, nil
}

type restyCtxLogger struct {
	ctx context.Context
	log *slog.Logger
}

func (l restyCtxLogger) Debugf(format string, v ...any) {
	msg := fmt.Sprintf(format, v...)
	l.log.DebugContext(l.ctx, msg)
}

func (l restyCtxLogger) Warnf(format string, v ...any) {
	msg := fmt.Sprintf(format, v...)
	l.log.WarnContext(l.ctx, msg)
}

func (l restyCtxLogger) Errorf(format string, v ...any) {
	msg := fmt.Sprintf(format, v...)
	l.log.ErrorContext(l.ctx, msg)
}