package sendico

import (
	"bytes"
	"context"
	"encoding/json"
	"io"
	"mime/multipart"
	"net/http"
	"strconv"
	"time"

	"git.sendico.io/tech/sxchnge/product/identity"
	merrors "git.sendico.io/tech/sxchnge/shared/errors"
)

type profileDTO struct {
	FullName         string `json:"full_name"`
	DateOfBirth      string `json:"date_of_birth"`
	ResidenceCountry string `json:"residence_country"`
	Email            string `json:"email"`
	CustomerRef      string `json:"external_customer_ref"`
}
type verificationDTO struct {
	SubjectRef     string     `json:"subject_ref"`
	SubmissionRef  string     `json:"submission_ref"`
	Status         string     `json:"status"`
	Reason         string     `json:"reason"`
	Profile        profileDTO `json:"profile"`
	UpgradePending bool       `json:"upgrade_pending"`
}
type policyDTO struct {
	Tier       string     `json:"tier"`
	ProfileRef string     `json:"profile_ref"`
	Entries    []limitDTO `json:"entries"`
}
type limitDTO struct {
	Operation string `json:"operation"`
	Period    string `json:"period"`
	Currency  string `json:"currency"`
	Cap       string `json:"cap"`
	Remaining string `json:"remaining"`
	Used      string `json:"used"`
	Reserved  string `json:"reserved"`
}

func (c *Client) identityRequest(ctx context.Context, subject, suffix, method, contentType string, body []byte, dst any) error {
	if !validRef(subject) {
		return merrors.InvalidArgument("invalid bound subject")
	}
	token, err := c.token()
	if err != nil {
		return err
	}
	req, err := http.NewRequestWithContext(ctx, method, c.base+"/identity_facts/"+c.config.OrganizationID+"/proofs/"+subject+suffix, bytes.NewReader(body))
	if err != nil {
		return merrors.OpaqueWrap(merrors.ErrServiceUnavailable, err, "create identity request")
	}
	req.Header.Set("Authorization", "Bearer "+token)
	if contentType != "" {
		req.Header.Set("Content-Type", contentType)
	}
	// Uploads need a longer bound than small sign-up receipts. The base client is
	// copied so concurrent sign-up operations keep their own four-second timeout.
	client := *c.http
	client.Timeout = 60 * time.Second
	res, err := client.Do(req)
	if err != nil {
		return merrors.OpaqueWrap(merrors.ErrServiceUnavailable, err, "identity provider request failed")
	}
	defer func() { _ = res.Body.Close() }()
	switch res.StatusCode {
	case http.StatusOK:
	case http.StatusBadRequest, http.StatusRequestEntityTooLarge:
		return merrors.InvalidArgument("identity profile or photos were not accepted")
	case http.StatusConflict:
		return merrors.DataConflict("identity submission changed; refresh")
	case http.StatusForbidden:
		return merrors.PermissionDenied("identity resource unavailable")
	case http.StatusTooManyRequests:
		retry := 60
		if seconds, parseErr := strconv.Atoi(res.Header.Get("Retry-After")); parseErr == nil && seconds > 0 && seconds <= 86400 {
			retry = seconds
		}
		return merrors.WithThrottle(merrors.ErrServiceUnavailable, "identity", time.Duration(retry)*time.Second, "identity submission temporarily limited")
	default:
		return merrors.ServiceUnavailable("identity provider unavailable")
	}
	var envelope struct {
		Status string          `json:"status"`
		Data   json.RawMessage `json:"data"`
	}
	decoder := json.NewDecoder(io.LimitReader(res.Body, 256*1024+1))
	if err := decoder.Decode(&envelope); err != nil {
		return merrors.OpaqueWrap(merrors.ErrServiceUnavailable, err, "decode identity response")
	}
	var extra any
	if decoder.Decode(&extra) != io.EOF || envelope.Status != "success" {
		return merrors.ServiceUnavailable("invalid identity response")
	}
	if err := json.Unmarshal(envelope.Data, dst); err != nil {
		return merrors.OpaqueWrap(merrors.ErrServiceUnavailable, err, "decode identity payload")
	}
	return nil
}
func mapVerification(dto verificationDTO, subject string) (identity.Verification, error) {
	if dto.SubjectRef != subject {
		return identity.Verification{}, merrors.ServiceUnavailable("identity response scope mismatch")
	}
	switch dto.Status {
	case "unverified", "pending", "approved", "changesRequested", "denied":
	default:
		return identity.Verification{}, merrors.ServiceUnavailable("invalid identity status")
	}
	if dto.Status == "approved" && dto.UpgradePending {
		dto.Status = "pending"
	}
	if dto.Status != "unverified" && !validRef(dto.SubmissionRef) {
		return identity.Verification{}, merrors.ServiceUnavailable("invalid identity receipt")
	}
	profile := identity.Profile{FullName: dto.Profile.FullName, DateOfBirth: dto.Profile.DateOfBirth, ResidenceCountry: dto.Profile.ResidenceCountry}
	if dto.Status != "unverified" {
		if err := profile.Validate(); err != nil {
			return identity.Verification{}, merrors.OpaqueWrap(merrors.ErrServiceUnavailable, err, "invalid identity profile response")
		}
	}
	return identity.Verification{Status: dto.Status, UpgradePending: dto.UpgradePending, Reason: dto.Reason, SubmissionID: dto.SubmissionRef, Profile: profile}, nil
}
func (c *Client) Verification(ctx context.Context, subject string) (identity.Verification, error) {
	var dto verificationDTO
	if err := c.identityRequest(ctx, subject, "", http.MethodGet, "", nil, &dto); err != nil {
		return identity.Verification{}, err
	}
	return mapVerification(dto, subject)
}
func (c *Client) SubmitVerification(ctx context.Context, subject, key string, p identity.Profile, f identity.Facts, document, selfie []byte) (identity.Verification, error) {
	var body bytes.Buffer
	writer := multipart.NewWriter(&body)
	profile, err := json.Marshal(profileDTO{FullName: p.FullName, DateOfBirth: p.DateOfBirth, ResidenceCountry: p.ResidenceCountry, Email: f.Email, CustomerRef: f.CustomerRef})
	if err != nil {
		return identity.Verification{}, merrors.OpaqueWrap(merrors.ErrInternal, err, "encode identity profile")
	}
	if err = writer.WriteField("profile", string(profile)); err != nil {
		return identity.Verification{}, err
	}
	if err = writer.WriteField("source_submission_ref", key); err != nil {
		return identity.Verification{}, err
	}
	for i, data := range [][]byte{document, selfie} {
		name := "document"
		if i == 1 {
			name = "selfie"
		}
		part, writeErr := writer.CreateFormFile(name, name)
		if writeErr != nil {
			return identity.Verification{}, writeErr
		}
		if _, writeErr = part.Write(data); writeErr != nil {
			return identity.Verification{}, writeErr
		}
	}
	if err = writer.Close(); err != nil {
		return identity.Verification{}, err
	}
	var dto verificationDTO
	if err = c.identityRequest(ctx, subject, "", http.MethodPost, writer.FormDataContentType(), body.Bytes(), &dto); err != nil {
		return identity.Verification{}, err
	}
	return mapVerification(dto, subject)
}
func (c *Client) Limits(ctx context.Context, subject string) (identity.Limits, error) {
	var dto policyDTO
	if err := c.identityRequest(ctx, subject, "/limits", http.MethodGet, "", nil, &dto); err != nil {
		return identity.Limits{}, err
	}
	if (dto.Tier != "basic" && dto.Tier != "verified") || dto.ProfileRef == "" || dto.Entries == nil {
		return identity.Limits{}, merrors.ServiceUnavailable("invalid limits response")
	}
	entries := make([]identity.Limit, 0, len(dto.Entries))
	for _, v := range dto.Entries {
		entries = append(entries, identity.Limit{Operation: v.Operation, Period: v.Period, Currency: v.Currency, Cap: v.Cap, Remaining: v.Remaining, Used: v.Used, Reserved: v.Reserved})
	}
	return identity.Limits{Tier: dto.Tier, ProfileRef: dto.ProfileRef, Entries: entries}, nil
}