package api

import (
	"errors"
	"net/http"
	"strings"

	"git.golem15.com/golem15/summercms/modules/backpack"
	"git.golem15.com/golem15/summercms/modules/bouncer"
	"git.golem15.com/golem15/summercms/modules/cabana"
	"git.golem15.com/golem15/summercms/modules/wire"
	"gorm.io/gorm"
)

const (
	errAuthenticationRequired = "Authentication required"
	errInsufficientPerms      = "Insufficient permissions"
	errPublishPermission      = "You do not have permission to publish posts"
	errEditPermission         = "You do not have permission to edit this post"
	errPostNotFound           = "Post not found"
	errImageNotFound          = "Image not found"
	errValidationFailed       = "Validation failed"
	msgPostDeleted            = "Post deleted"
	msgImageRemoved           = "Image removed"

	permAccessPosts      = "golem15.journal.access_posts"
	permAccessOtherPosts = "golem15.journal.access_other_posts"
	permAccessPublish    = "golem15.journal.access_publish"

	journalCover = "golem15.journal.*"
)

func writeAPIError(w http.ResponseWriter, status int, message string) {
	wire.WriteJSON(w, status, map[string]any{"error": message})
}

func writeValidation(w http.ResponseWriter, errs map[string][]string) {
	wire.WriteJSON(w, http.StatusUnprocessableEntity, map[string]any{
		"error":  errValidationFailed,
		"errors": errs,
	})
}

func writeAuthRequired(w http.ResponseWriter, _ error) {
	writeAPIError(w, http.StatusUnauthorized, errAuthenticationRequired)
}

func hasBearer(r *http.Request) bool {
	if r == nil {
		return false
	}
	h := strings.TrimSpace(r.Header.Get("Authorization"))
	token, ok := strings.CutPrefix(h, "Bearer ")
	return ok && strings.TrimSpace(token) != ""
}

// resolveError maps cabana.ResolveBackend errors to the PHP Journal API bodies.
func resolveError(w http.ResponseWriter, err error) {
	if errors.Is(err, cabana.ErrTokenScope) {
		writeAPIError(w, http.StatusForbidden, errInsufficientPerms)
		return
	}
	writeAuthRequired(w, err)
}

// optionalBackendPrincipal verifies a backend JWT or personal API token only
// when Authorization Bearer is present. Failure is anonymous: public GET must
// not 401. Uses cabana.ResolveBackend with cover golem15.journal.*.
func optionalBackendPrincipal(app *backpack.App, r *http.Request) *http.Request {
	if r == nil || !hasBearer(r) {
		return r
	}
	out, _, err := cabana.ResolveBackend(app, r, journalCover)
	if err != nil || out == nil {
		return r
	}
	return out
}

// requireBackendPrincipal authenticates a backend JWT or personal API token
// and writes the PHP {error:"Authentication required"} or
// {error:"Insufficient permissions"} body (D-15). It does not use cabana's
// admin unauthenticated envelope.
func requireBackendPrincipal(app *backpack.App, w http.ResponseWriter, r *http.Request) (*http.Request, *bouncer.Principal, bool) {
	out, pr, err := cabana.ResolveBackend(app, r, journalCover)
	if err != nil || pr == nil {
		resolveError(w, err)
		return r, nil, false
	}
	return out, pr, true
}

func isEditor(pr *bouncer.Principal) bool {
	return cabana.Allows(pr, []string{permAccessPosts})
}

func requireAccessPosts(w http.ResponseWriter, pr *bouncer.Principal) bool {
	if !cabana.Allows(pr, []string{permAccessPosts}) {
		writeAPIError(w, http.StatusForbidden, errInsufficientPerms)
		return false
	}
	return true
}

func gdb(app *backpack.App) (*gorm.DB, error) {
	if app == nil {
		return nil, errors.New("journal api: application is not configured")
	}
	db, ok := app.Lookup[*gorm.DB]()
	if !ok || db == nil {
		return nil, errors.New("journal api: database is not configured")
	}
	return db, nil
}