package handlers

import "database/sql"
import "encoding/json"
import "errors"
import "fmt"
import "net/http"
import "strings"

import "codit/internal/db"
import "codit/internal/gpg"
import "codit/internal/middleware"
import "codit/internal/models"

const personalGPGKeyUploadMaxBytes int64 = 256 * 1024

// gpgActor returns the acting user from the request context.
func (api *API) gpgActor(r *http.Request) (models.User, bool) {
	return middleware.UserFromContext(r.Context())
}

// canManageGPGKey reports whether the user may modify or delete the key.
// Admins may manage any key; a regular user may manage only their own
// personal keys.
func (api *API) canManageGPGKey(r *http.Request, keyID string, user models.User) bool {
	var owned bool
	var err error
	if user.IsAdmin {
		return true
	}
	owned, err = api.store(r).GPGKeyPersonalOwner(keyID, user.ID)
	if err != nil {
		return false
	}
	return owned
}

func (api *API) canManageProjectSigningKeys(r *http.Request, projectID string) bool {
	var user models.User
	var principal models.ServicePrincipal
	var ok bool
	var role string
	var err error

	user, ok = middleware.UserFromContext(r.Context())
	if ok {
		if user.IsAdmin { return true }
		role, err = api.store(r).GetProjectRoleForUser(projectID, user.ID)
		if err != nil { return false }
		return roleAllows(role, models.RoleAdmin)
	}

	principal, ok = middleware.PrincipalFromContext(r.Context())
	if !ok || principal.Disabled { return false }
	if principal.IsAdmin { return true }

	role, err = api.store(r).GetPrincipalProjectRole(principal.ID, projectID)
	if err != nil { return false }
	return roleAllows(role, models.RoleAdmin)
}

// ListMyGPGKeys returns the caller's registered personal (public-only) keys,
// used for commit/tag signature verification.
func (api *API) ListMyGPGKeys(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var user models.User
	var ok bool
	var keys []models.GPGKey
	var err error
	var i int
	user, ok = api.gpgActor(r)
	if !ok {
		WriteJSONWithErrorReason(w, r, http.StatusForbidden, "authentication required")
		return
	}
	keys, err = api.store(r).ListPersonalGPGKeys(user.ID)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	if keys == nil {
		keys = []models.GPGKey{}
	}
	for i = range keys {
		keys[i].CanManage = true
	}
	WriteJSON(w, http.StatusOK, keys)
}

// AddMyGPGKey registers a PUBLIC key (pasted by the user) for the caller. The
// private half is never sent or stored — the user keeps it locally to sign.
func (api *API) AddMyGPGKey(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var user models.User
	var ok bool
	var req struct {
		Name      string `json:"name"`
		PublicKey string `json:"public_key"`
	}
	var km gpg.KeyMaterial
	var key models.GPGKey
	var stored models.GPGKey
	var err error

	user, ok = api.gpgActor(r)
	if !ok {
		WriteJSONWithErrorReason(w, r, http.StatusForbidden, "authentication required")
		return
	}

	r.Body = http.MaxBytesReader(w, r.Body, personalGPGKeyUploadMaxBytes)
	err = json.NewDecoder(r.Body).Decode(&req)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "invalid request")
		return
	}

	if strings.TrimSpace(req.PublicKey) == "" {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "public key is required")
		return
	}

	km, err = gpg.ParsePublic(req.PublicKey)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "invalid public key: "+err.Error())
		return
	}

	key = api.buildPersonalKey(user.ID, req.Name, km)

	// it persists a public-only personal key, rejecting a
	// duplicate fingerprint already registered by any user.
	stored, err = api.store(r).CreateGPGKey(r.Context(), key, user.ID, "")
	if err != nil {
		if errors.Is(err, db.ErrGPGKeyAlreadyRegistered) {
			WriteJSONWithErrorReason(w, r, http.StatusConflict, "this key is already registered")
			return
		}
		if errors.Is(err, db.ErrPersonalGPGKeyLimitReached) {
			WriteJSONWithErrorReason(w, r, http.StatusConflict, "personal gpg key limit reached")
			return
		}
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	stored.CanManage = true
	WriteJSON(w, http.StatusOK, stored)
}

// GenerateMyGPGKey is a convenience: it generates a keypair, registers the
// PUBLIC half for the caller, and returns the PRIVATE key ONCE for the user to
// download and import locally. The private key is never stored server-side.
func (api *API) GenerateMyGPGKey(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var user models.User
	var ok bool
	var req struct {
		Name  string `json:"name"`
		Email string `json:"email"`
	}
	var km gpg.KeyMaterial
	var key models.GPGKey
	var stored models.GPGKey
	var err error
	user, ok = api.gpgActor(r)
	if !ok {
		WriteJSONWithErrorReason(w, r, http.StatusForbidden, "authentication required")
		return
	}
	err = json.NewDecoder(r.Body).Decode(&req)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "invalid request")
		return
	}
	if strings.TrimSpace(req.Name) == "" {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "name is required")
		return
	}
	km, err = gpg.Generate(req.Name, req.Email)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	key = api.buildPersonalKey(user.ID, req.Name, km)
	stored, err = api.store(r).CreateGPGKey(r.Context(), key, user.ID, "")
	if err != nil {
		if errors.Is(err, db.ErrGPGKeyAlreadyRegistered) {
			WriteJSONWithErrorReason(w, r, http.StatusConflict, "this key is already registered")
			return
		}
		if errors.Is(err, db.ErrPersonalGPGKeyLimitReached) {
			WriteJSONWithErrorReason(w, r, http.StatusConflict, "personal gpg key limit reached")
			return
		}
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	stored.CanManage = true
	// Return the private key once, for the user to save and import locally.
	WriteJSON(w, http.StatusOK, map[string]any{
		"key":         stored,
		"private_key": km.PrivateArmored,
		"public_key":  km.PublicArmored,
	})
}

// DeleteMyGPGKey removes one of the caller's registered personal keys.
func (api *API) DeleteMyGPGKey(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var user models.User
	var ok bool
	var owned bool
	var err error
	user, ok = api.gpgActor(r)
	if !ok {
		WriteJSONWithErrorReason(w, r, http.StatusForbidden, "authentication required")
		return
	}
	owned, err = api.store(r).GPGKeyPersonalOwner(params["id"], user.ID)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	if !owned {
		WriteJSONWithErrorReason(w, r, http.StatusForbidden, "not permitted")
		return
	}
	err = api.store(r).DeleteGPGKey(params["id"])
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	WriteJSON(w, http.StatusOK, map[string]string{"status": "deleted"})
}

// buildPersonalKey assembles a public-only personal GPGKey from key material.
func (api *API) buildPersonalKey(_ string, name string, km gpg.KeyMaterial) models.GPGKey {
	var key models.GPGKey
	key.Scope = models.GPGKeyScopePersonal
	key.Name = strings.TrimSpace(name)
	if key.Name == "" {
		key.Name = km.KeyID
	}
	key.Fingerprint = km.Fingerprint
	key.KeyID = km.KeyID
	key.PublicKey = km.PublicArmored
	key.PrivateKey = "" // public-only: never store the private half
	return key
}

// ListAllGPGKeys returns every key for admin oversight (admins may manage any).
func (api *API) ListAllGPGKeys(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var keys []models.GPGKey
	var err error
	var i int
	if !api.requireAdmin(w, r) {
		return
	}
	keys, err = api.store(r).ListGPGKeys()
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	if keys == nil {
		keys = []models.GPGKey{}
	}
	for i = range keys {
		keys[i].CanManage = true
	}
	WriteJSON(w, http.StatusOK, keys)
}

func (api *API) GetGPGKey(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var user models.User
	var ok bool
	var key models.GPGKey
	var err error
	user, ok = api.gpgActor(r)
	if !ok {
		WriteJSONWithErrorReason(w, r, http.StatusForbidden, "authentication required")
		return
	}
	key, err = api.store(r).GetGPGKey(params["id"])
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusNotFound, "gpg key not found")
		return
	}
	// A user may view their own personal key; admins may view any key.
	if !api.canManageGPGKey(r, key.ID, user) {
		WriteJSONWithErrorReason(w, r, http.StatusForbidden, "not permitted")
		return
	}
	key.CanManage = true
	WriteJSON(w, http.StatusOK, key)
}

// createGlobalGPGKey persists an organization-wide (global) signing key.
// Personal keys are public-only and registered via /api/me/gpg-keys instead.
func (api *API) createGlobalGPGKey(w http.ResponseWriter, r *http.Request, name string, km gpg.KeyMaterial) {
	var key models.GPGKey
	var err error
	key.Scope = models.GPGKeyScopeGlobal
	key.Name = strings.TrimSpace(name)
	key.Fingerprint = km.Fingerprint
	key.KeyID = km.KeyID
	key.PublicKey = km.PublicArmored
	key.PrivateKey = km.PrivateArmored

	key, err = api.store(r).CreateGPGKey(r.Context(), key, "", "")
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}

	key.CanManage = true
	WriteJSON(w, http.StatusOK, key)
}

func (api *API) GenerateGPGKey(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var req struct {
		Name  string `json:"name"`
		Email string `json:"email"`
	}
	var km gpg.KeyMaterial
	var err error
	if !api.requireAdmin(w, r) {
		return
	}
	err = json.NewDecoder(r.Body).Decode(&req)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "invalid request")
		return
	}
	if strings.TrimSpace(req.Name) == "" {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "name is required")
		return
	}
	km, err = gpg.Generate(req.Name, req.Email)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	api.createGlobalGPGKey(w, r, req.Name, km)
}

func (api *API) ImportGPGKey(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var req struct {
		Name       string `json:"name"`
		PrivateKey string `json:"private_key"`
	}
	var km gpg.KeyMaterial
	var err error
	if !api.requireAdmin(w, r) {
		return
	}
	err = json.NewDecoder(r.Body).Decode(&req)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "invalid request")
		return
	}
	if strings.TrimSpace(req.Name) == "" {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "name is required")
		return
	}
	if strings.TrimSpace(req.PrivateKey) == "" {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "private key is required")
		return
	}
	km, err = gpg.Parse(req.PrivateKey)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "invalid private key: "+err.Error())
		return
	}
	api.createGlobalGPGKey(w, r, req.Name, km)
}

// ListProjectSigningKeys returns the signing keys owned by the project. Any
// project viewer may list them.
func (api *API) ListProjectSigningKeys(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var keys []models.GPGKey
	var err error
	var i int
	var canManage bool
	if !api.requireProjectRole(w, r, params["projectId"], models.RoleViewer) {
		return
	}
	canManage = api.canManageProjectSigningKeys(r, params["projectId"])
	keys, err = api.store(r).ListProjectGPGKeys(params["projectId"])
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	if keys == nil {
		keys = []models.GPGKey{}
	}
	for i = range keys {
		keys[i].CanManage = canManage
	}
	WriteJSON(w, http.StatusOK, keys)
}

func (api *API) GetProjectSigningKey(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var key models.GPGKey
	var belongs bool
	var err error
	var canManage bool
	if !api.requireProjectRole(w, r, params["projectId"], models.RoleViewer) {
		return
	}
	canManage = api.canManageProjectSigningKeys(r, params["projectId"])
	belongs, err = api.store(r).GPGKeyBelongsToProject(params["keyId"], params["projectId"])
	if err != nil || !belongs {
		WriteJSONWithErrorReason(w, r, http.StatusNotFound, "gpg key not found")
		return
	}
	key, err = api.store(r).GetGPGKey(params["keyId"])
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusNotFound, "gpg key not found")
		return
	}
	key.CanManage = canManage
	WriteJSON(w, http.StatusOK, key)
}

// ListSelectableSigningKeys returns the keys a project may sign with: the
// project's own keys plus all org keys. Used to populate a repo's signing-key
// selector.
func (api *API) ListSelectableSigningKeys(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var keys []models.GPGKey
	var err error
	if !api.requireProjectRole(w, r, params["projectId"], models.RoleWriter) {
		return
	}
	keys, err = api.store(r).ListSelectableGPGKeys(params["projectId"])
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	if keys == nil {
		keys = []models.GPGKey{}
	}
	WriteJSON(w, http.StatusOK, keys)
}

// createProjectSigningKey persists a project-scoped key after the request has
// been authorized as a project admin.
func (api *API) createProjectSigningKey(w http.ResponseWriter, r *http.Request, projectID string, name string, km gpg.KeyMaterial) {
	var key models.GPGKey
	var err error

	key = models.GPGKey{
		Name:        strings.TrimSpace(name),
		Fingerprint: km.Fingerprint,
		KeyID:       km.KeyID,
		PublicKey:   km.PublicArmored,
		PrivateKey:  km.PrivateArmored,
		Scope:       models.GPGKeyScopeProject,
	}

	key, err = api.store(r).CreateGPGKey(r.Context(), key, "", projectID)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	key.CanManage = true
	WriteJSON(w, http.StatusOK, key)
}

func (api *API) GenerateProjectSigningKey(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var req struct {
		Name  string `json:"name"`
		Email string `json:"email"`
	}
	var km gpg.KeyMaterial
	var err error

	if !api.requireProjectRole(w, r, params["projectId"], models.RoleAdmin) { return }

	err = json.NewDecoder(r.Body).Decode(&req)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "invalid request")
		return
	}
	if strings.TrimSpace(req.Name) == "" {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "name is required")
		return
	}
	km, err = gpg.Generate(req.Name, req.Email)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	api.createProjectSigningKey(w, r, params["projectId"], req.Name, km)
}

func (api *API) ImportProjectSigningKey(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var req struct {
		Name       string `json:"name"`
		PrivateKey string `json:"private_key"`
	}
	var km gpg.KeyMaterial
	var err error

	if !api.requireProjectRole(w, r, params["projectId"], models.RoleAdmin) { return }

	err = json.NewDecoder(r.Body).Decode(&req)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "invalid request")
		return
	}
	if strings.TrimSpace(req.Name) == "" {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "name is required")
		return
	}
	if strings.TrimSpace(req.PrivateKey) == "" {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "private key is required")
		return
	}
	km, err = gpg.Parse(req.PrivateKey)
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusBadRequest, "invalid private key: "+err.Error())
		return
	}
	api.createProjectSigningKey(w, r, params["projectId"], req.Name, km)
}

func (api *API) DeleteProjectSigningKey(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var belongs bool
	var usage []models.GPGKeyRepoUsage
	var err error

	if !api.requireProjectRole(w, r, params["projectId"], models.RoleAdmin) { return }

	belongs, err = api.store(r).GPGKeyBelongsToProject(params["keyId"], params["projectId"])
	if err != nil || !belongs {
		WriteJSONWithErrorReason(w, r, http.StatusNotFound, "gpg key not found")
		return
	}
	usage, err = api.store(r).ListReposUsingGPGKey(params["keyId"])
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	if len(usage) > 0 {
		var noun string
		noun = "repository"
		if len(usage) != 1 { noun = "repositories" }
		WriteJSONWithErrorReason(w, r, http.StatusConflict, fmt.Sprintf("signing key is in use by %d %s; remove it from them first", len(usage), noun))
		return
	}
	err = api.store(r).DeleteGPGKey(params["keyId"])
	if err != nil {
		if err == sql.ErrNoRows {
			WriteJSONWithErrorReason(w, r, http.StatusNotFound, "gpg key not found")
			return
		}
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	WriteJSON(w, http.StatusOK, map[string]string{"status": "deleted"})
}

func (api *API) DeleteGPGKey(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var user models.User
	var usage []models.GPGKeyRepoUsage
	var ok bool
	var err error

	user, ok = api.gpgActor(r)
	if !ok {
		WriteJSONWithErrorReason(w, r, http.StatusForbidden, "authentication required")
		return
	}
	if !api.canManageGPGKey(r, params["id"], user) {
		WriteJSONWithErrorReason(w, r, http.StatusForbidden, "not permitted")
		return
	}
	usage, err = api.store(r).ListReposUsingGPGKey(params["id"])
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	if len(usage) > 0 {
		var noun string
		noun = "repository"
		if len(usage) != 1 { noun = "repositories" }
		WriteJSONWithErrorReason(w, r, http.StatusConflict, fmt.Sprintf("signing key is in use by %d %s; remove it from them first", len(usage), noun))
		return
	}
	err = api.store(r).DeleteGPGKey(params["id"])
	if err != nil {
		if err == sql.ErrNoRows {
			WriteJSONWithErrorReason(w, r, http.StatusNotFound, "gpg key not found")
			return
		}
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	WriteJSON(w, http.StatusOK, map[string]string{"status": "deleted"})
}

// GPGKeyUsage returns the repositories that reference this key as their signing
// key, so the admin/owner can see who's using it before deleting.
func (api *API) GPGKeyUsage(w http.ResponseWriter, r *http.Request, params map[string]string) {
	var key models.GPGKey
	var user models.User
	var ok bool
	var usage []models.GPGKeyRepoUsage
	var err error

	user, ok = api.gpgActor(r)
	if !ok {
		WriteJSONWithErrorReason(w, r, http.StatusForbidden, "authentication required")
		return
	}
	key, err = api.store(r).GetGPGKey(params["id"])
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusNotFound, "gpg key not found")
		return
	}
	if !api.canManageGPGKey(r, params["id"], user) {
		if key.Scope != models.GPGKeyScopeProject || key.OwnerProjectPublicID == "" || !api.canManageProjectSigningKeys(r, key.OwnerProjectPublicID) {
			WriteJSONWithErrorReason(w, r, http.StatusForbidden, "not permitted")
			return
		}
	}
	usage, err = api.store(r).ListReposUsingGPGKey(params["id"])
	if err != nil {
		WriteJSONWithErrorReason(w, r, http.StatusInternalServerError, err.Error())
		return
	}
	if usage == nil {
		usage = []models.GPGKeyRepoUsage{}
	}
	WriteJSON(w, http.StatusOK, usage)
}