// Copyright 2016 The Gogs Authors. All rights reserved.
// Copyright 2019 The Gitea Authors and MarketAlly. All rights reserved.
// SPDX-License-Identifier: MIT

package context

import (
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"slices"
	"strconv"
	"strings"

	"code.gitea.io/gitea/models/unit"
	user_model "code.gitea.io/gitea/models/user"
	"code.gitea.io/gitea/modules/cache"
	apierrors "code.gitea.io/gitea/modules/errors"
	"code.gitea.io/gitea/modules/git"
	"code.gitea.io/gitea/modules/gitrepo"
	"code.gitea.io/gitea/modules/httpcache"
	"code.gitea.io/gitea/modules/log"
	"code.gitea.io/gitea/modules/setting"
	"code.gitea.io/gitea/modules/util"
	"code.gitea.io/gitea/modules/web"
	"code.gitea.io/gitea/modules/web/middleware"
	web_types "code.gitea.io/gitea/modules/web/types"
)

// APIContext is a specific context for API service
// ATTENTION: This struct should never be manually constructed in routes/services,
// it has many internal details which should be carefully prepared by the framework.
// If it is abused, it would cause strange bugs like panic/resource-leak.
type APIContext struct {
	*Base

	Cache cache.StringCache

	Doer        *user_model.User // current signed-in user
	IsSigned    bool
	IsBasicAuth bool

	ContextUser *user_model.User // the user which is being visited, in most cases it differs from Doer

	Repo       *Repository
	Org        *APIOrganization
	Package    *Package
	PublicOnly bool // Whether the request is for a public endpoint
}

func init() {
	web.RegisterResponseStatusProvider[*APIContext](func(req *http.Request) web_types.ResponseStatusProvider {
		return req.Context().Value(apiContextKey).(*APIContext)
	})
}

// Currently, we have the following common fields in error response:
// * message: the message for end users (it shouldn't be used for error type detection)
//            if we need to indicate some errors, we should introduce some new fields like ErrorCode or ErrorType
// * url:     the swagger document URL
// * request_id: the unique request ID for tracing (X-Request-ID header)
//
// RFC 7807 Problem Details fields are also included for standard compliance:
// * type:     A URI reference identifying the problem type (default: "about:blank")
// * title:    A short, human-readable summary of the problem type
// * status:   The HTTP status code
// * detail:   A human-readable explanation specific to this occurrence
// * instance: A URI reference identifying this specific occurrence (request ID)

// APIError is error format response following RFC 7807 Problem Details
// swagger:response error
type APIError struct {
	// Legacy fields (maintained for backward compatibility)
	Message   string `json:"message"`
	URL       string `json:"url"`
	RequestID string `json:"request_id,omitempty"`

	// RFC 7807 Problem Details fields
	Type     string `json:"type,omitempty"`     // URI reference identifying the problem type
	Title    string `json:"title,omitempty"`    // Short summary of the problem type
	Status   int    `json:"status,omitempty"`   // HTTP status code
	Detail   string `json:"detail,omitempty"`   // Explanation specific to this occurrence
	Instance string `json:"instance,omitempty"` // URI reference for this specific occurrence
}

// APIValidationError is error format response related to input validation
// swagger:response validationError
type APIValidationError struct {
	Message string `json:"message"`
	URL     string `json:"url"`
}

// APIInvalidTopicsError is error format response to invalid topics
// swagger:response invalidTopicsError
type APIInvalidTopicsError struct {
	Message       string   `json:"message"`
	InvalidTopics []string `json:"invalidTopics"`
}

// APIEmpty is an empty response
// swagger:response empty
type APIEmpty struct{}

// APIForbiddenError is a forbidden error response
// swagger:response forbidden
type APIForbiddenError struct {
	APIError
}

// APINotFound is a not found empty response
// swagger:response notFound
type APINotFound struct{}

// APIConflict is a conflict empty response
// swagger:response conflict
type APIConflict struct{}

// APIRedirect is a redirect response
// swagger:response redirect
type APIRedirect struct{}

// APIString is a string response
// swagger:response string
type APIString string

// APIRepoArchivedError is an error that is raised when an archived repo should be modified
// swagger:response repoArchivedError
type APIRepoArchivedError struct {
	APIError
}

// APIErrorInternal responds with error message, status is 500
func (ctx *APIContext) APIErrorInternal(err error) {
	ctx.apiErrorInternal(1, err)
}

func (ctx *APIContext) apiErrorInternal(skip int, err error) {
	requestID := middleware.GetRequestID(ctx.Req.Context())
	log.ErrorWithSkip(skip+1, "InternalServerError [%s]: %v", requestID, err)

	var message string
	var detail string
	if !setting.IsProd || (ctx.Doer != nil && ctx.Doer.IsAdmin) {
		message = err.Error()
		detail = err.Error()
	} else {
		message = "Internal Server Error"
	}

	ctx.JSON(http.StatusInternalServerError, APIError{
		// Legacy fields
		Message:   message,
		URL:       setting.API.SwaggerURL,
		RequestID: requestID,
		// RFC 7807 fields
		Type:     "about:blank",
		Title:    "Internal Server Error",
		Status:   http.StatusInternalServerError,
		Detail:   detail,
		Instance: requestID,
	})
}

// APIError responds with an error message to client with given obj as the message.
// If status is 500, also it prints error to log.
func (ctx *APIContext) APIError(status int, obj any) {
	requestID := middleware.GetRequestID(ctx.Req.Context())

	var message string
	if err, ok := obj.(error); ok {
		message = err.Error()
	} else {
		message = fmt.Sprintf("%s", obj)
	}

	detail := message
	if status == http.StatusInternalServerError {
		log.ErrorWithSkip(1, "APIError [%s]: %s", requestID, message)

		if setting.IsProd && !(ctx.Doer != nil && ctx.Doer.IsAdmin) {
			message = "Internal Server Error"
			detail = ""
		}
	}

	// Get HTTP status text as the title
	title := http.StatusText(status)
	if title == "" {
		title = "Error"
	}

	ctx.JSON(status, APIError{
		// Legacy fields
		Message:   message,
		URL:       setting.API.SwaggerURL,
		RequestID: requestID,
		// RFC 7807 fields
		Type:     "about:blank",
		Title:    title,
		Status:   status,
		Detail:   detail,
		Instance: requestID,
	})
}

// APIErrorWithCode responds with a structured error using the new error code system.
// This provides machine-readable error codes for AI and automation tools.
func (ctx *APIContext) APIErrorWithCode(code apierrors.ErrorCode, details ...map[string]any) {
	requestID := middleware.GetRequestID(ctx.Req.Context())

	apiErr := apierrors.NewAPIError(code, requestID)
	if len(details) > 0 && details[0] != nil {
		apiErr.WithDetails(details[0])
	}

	if code.HTTPStatus() == http.StatusInternalServerError {
		log.Error("APIError [%s] %s: %s", requestID, code, code.Message())
	}

	ctx.JSON(code.HTTPStatus(), apiErr.Response())
}

// APIErrorWithCodeAndMessage responds with a structured error with a custom message.
func (ctx *APIContext) APIErrorWithCodeAndMessage(code apierrors.ErrorCode, message string, details ...map[string]any) {
	requestID := middleware.GetRequestID(ctx.Req.Context())

	apiErr := apierrors.NewAPIError(code, requestID).WithMessage(message)
	if len(details) > 0 && details[0] != nil {
		apiErr.WithDetails(details[0])
	}

	if code.HTTPStatus() == http.StatusInternalServerError {
		log.Error("APIError [%s] %s: %s", requestID, code, message)
	}

	ctx.JSON(code.HTTPStatus(), apiErr.Response())
}

// APIValidationError responds with a validation error including field-level details.
func (ctx *APIContext) APIValidationError(errors ...apierrors.ValidationError) {
	requestID := middleware.GetRequestID(ctx.Req.Context())
	validationErr := apierrors.NewValidationError(requestID, errors...)
	ctx.JSON(http.StatusBadRequest, validationErr)
}

type apiContextKeyType struct{}

var apiContextKey = apiContextKeyType{}

// GetAPIContext returns a context for API routes
func GetAPIContext(req *http.Request) *APIContext {
	return req.Context().Value(apiContextKey).(*APIContext)
}

func genAPILinks(curURL *url.URL, total, pageSize, curPage int) []string {
	page := NewPagination(total, pageSize, curPage, 0)
	paginater := page.Paginater
	links := make([]string, 0, 4)

	if paginater.HasNext() {
		u := *curURL
		queries := u.Query()
		queries.Set("page", strconv.Itoa(paginater.Next()))
		u.RawQuery = queries.Encode()

		links = append(links, fmt.Sprintf("<%s%s>; rel=\"next\"", setting.AppURL, u.RequestURI()[1:]))
	}
	if !paginater.IsLast() {
		u := *curURL
		queries := u.Query()
		queries.Set("page", strconv.Itoa(paginater.TotalPages()))
		u.RawQuery = queries.Encode()

		links = append(links, fmt.Sprintf("<%s%s>; rel=\"last\"", setting.AppURL, u.RequestURI()[1:]))
	}
	if !paginater.IsFirst() {
		u := *curURL
		queries := u.Query()
		queries.Set("page", "1")
		u.RawQuery = queries.Encode()

		links = append(links, fmt.Sprintf("<%s%s>; rel=\"first\"", setting.AppURL, u.RequestURI()[1:]))
	}
	if paginater.HasPrevious() {
		u := *curURL
		queries := u.Query()
		queries.Set("page", strconv.Itoa(paginater.Previous()))
		u.RawQuery = queries.Encode()

		links = append(links, fmt.Sprintf("<%s%s>; rel=\"prev\"", setting.AppURL, u.RequestURI()[1:]))
	}
	return links
}

// SetLinkHeader sets pagination link header by given total number and page size.
func (ctx *APIContext) SetLinkHeader(total, pageSize int) {
	links := genAPILinks(ctx.Req.URL, total, pageSize, ctx.FormInt("page"))

	if len(links) > 0 {
		ctx.RespHeader().Set("Link", strings.Join(links, ","))
		ctx.AppendAccessControlExposeHeaders("Link")
	}
}

// APIContexter returns APIContext middleware
func APIContexter() func(http.Handler) http.Handler {
	return func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
			base := NewBaseContext(w, req)
			ctx := &APIContext{
				Base:  base,
				Cache: cache.GetCache(),
				Repo:  &Repository{PullRequest: &PullRequest{}},
				Org:   &APIOrganization{},
			}

			ctx.SetContextValue(apiContextKey, ctx)

			// FIXME: GLOBAL-PARSE-FORM: see more details in another FIXME comment
			if ctx.Req.Method == http.MethodPost && strings.Contains(ctx.Req.Header.Get("Content-Type"), "multipart/form-data") {
				if !ctx.ParseMultipartForm() {
					return
				}
			}

			httpcache.SetCacheControlInHeader(ctx.Resp.Header(), &httpcache.CacheControlOptions{NoTransform: true})
			ctx.Resp.Header().Set(`X-Frame-Options`, setting.CORSConfig.XFrameOptions)

			next.ServeHTTP(ctx.Resp, ctx.Req)
		})
	}
}

// APIErrorNotFound handles 404s for APIContext
// String will replace message, errors will be added to a slice
func (ctx *APIContext) APIErrorNotFound(objs ...any) {
	requestID := middleware.GetRequestID(ctx.Req.Context())

	var message string
	var errs []string
	for _, obj := range objs {
		// Ignore nil
		if obj == nil {
			continue
		}

		if err, ok := obj.(error); ok {
			errs = append(errs, err.Error())
		} else {
			message = obj.(string)
		}
	}

	finalMessage := util.IfZero(message, "not found")
	ctx.JSON(http.StatusNotFound, map[string]any{
		// Legacy fields
		"message":    finalMessage, // do not use locale in API
		"url":        setting.API.SwaggerURL,
		"errors":     errs,
		"request_id": requestID,
		// RFC 7807 fields
		"type":     "about:blank",
		"title":    "Not Found",
		"status":   http.StatusNotFound,
		"detail":   finalMessage,
		"instance": requestID,
	})
}

// ReferencesGitRepo injects the GitRepo into the Context
// you can optional skip the IsEmpty check
func ReferencesGitRepo(allowEmpty ...bool) func(ctx *APIContext) {
	return func(ctx *APIContext) {
		// Empty repository does not have reference information.
		if ctx.Repo.Repository.IsEmpty && !(len(allowEmpty) != 0 && allowEmpty[0]) {
			return
		}

		// For API calls.
		if ctx.Repo.GitRepo == nil {
			var err error
			ctx.Repo.GitRepo, err = gitrepo.RepositoryFromRequestContextOrOpen(ctx, ctx.Repo.Repository)
			if err != nil {
				ctx.APIErrorInternal(err)
				return
			}
		}
	}
}

// RepoRefForAPI handles repository reference names when the ref name is not explicitly given
func RepoRefForAPI(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		ctx := GetAPIContext(req)

		if ctx.Repo.Repository.IsEmpty {
			ctx.APIErrorNotFound("repository is empty")
			return
		}

		if ctx.Repo.GitRepo == nil {
			panic("no GitRepo, forgot to call the middleware?") // it is a programming error
		}

		refName, refType, _ := getRefNameLegacy(ctx.Base, ctx.Repo, ctx.PathParam("*"), ctx.FormTrim("ref"))
		var err error
		switch refType {
		case git.RefTypeBranch:
			ctx.Repo.Commit, err = ctx.Repo.GitRepo.GetBranchCommit(refName)
		case git.RefTypeTag:
			ctx.Repo.Commit, err = ctx.Repo.GitRepo.GetTagCommit(refName)
		case git.RefTypeCommit:
			ctx.Repo.Commit, err = ctx.Repo.GitRepo.GetCommit(refName)
		}
		if ctx.Repo.Commit == nil || errors.Is(err, util.ErrNotExist) {
			ctx.APIErrorNotFound("unable to find a git ref")
			return
		} else if err != nil {
			ctx.APIErrorInternal(err)
			return
		}
		ctx.Repo.CommitID = ctx.Repo.Commit.ID.String()
		next.ServeHTTP(w, req)
	})
}

// HasAPIError returns true if error occurs in form validation.
func (ctx *APIContext) HasAPIError() bool {
	hasErr, ok := ctx.Data["HasError"]
	if !ok {
		return false
	}
	return hasErr.(bool)
}

// GetErrMsg returns error message in form validation.
func (ctx *APIContext) GetErrMsg() string {
	msg, _ := ctx.Data["ErrorMsg"].(string)
	if msg == "" {
		msg = "invalid form data"
	}
	return msg
}

// NotFoundOrServerError use error check function to determine if the error
// is about not found. It responds with 404 status code for not found error,
// or error context description for logging purpose of 500 server error.
func (ctx *APIContext) NotFoundOrServerError(err error) {
	if errors.Is(err, util.ErrNotExist) {
		ctx.JSON(http.StatusNotFound, nil)
		return
	}
	ctx.APIErrorInternal(err)
}

// IsUserSiteAdmin returns true if current user is a site admin
func (ctx *APIContext) IsUserSiteAdmin() bool {
	return ctx.IsSigned && ctx.Doer.IsAdmin
}

// IsUserRepoAdmin returns true if current user is admin in current repo
func (ctx *APIContext) IsUserRepoAdmin() bool {
	return ctx.Repo.IsAdmin()
}

// IsUserRepoWriter returns true if current user has "write" privilege in current repo
func (ctx *APIContext) IsUserRepoWriter(unitTypes []unit.Type) bool {
	return slices.ContainsFunc(unitTypes, ctx.Repo.CanWrite)
}
