//go:build summercms_mcp

package surf

import (
	"fmt"
	"net/http"
	"net/netip"
	"strings"

	"git.golem15.com/golem15/summercms/modules/backpack"
	"git.golem15.com/golem15/summercms/modules/pact"
	"git.golem15.com/golem15/summercms/modules/party"
	"git.golem15.com/golem15/summercms/modules/pier"
)

// Binaries built with the summercms_mcp tag (MCPBuildTag) link the MCP
// module: this file sets the mount hook BuildRouter calls when mcp.enabled
// is true, with an adapter that gives pier the route table, the compiled
// handler lookup and the two mount kinds without pier importing surf.
func init() {
	mountPier = func(r *Router, app *backpack.App, plugins []party.Plugin) error {
		return pier.Mount(pierHost{r: r, trusted: TrustedProxies(app.Config)}, app, plugins)
	}
}

// pierHost adapts a Router to pier.Host. trusted holds http.trusted_proxies
// for ClientIP.
type pierHost struct {
	r       *Router
	trusted []netip.Prefix
}

// ClientIP answers the request's client address with the application's
// trusted proxies applied, the same rule the throttle middleware uses; pier
// puts it on the token resolvers' context.
func (h pierHost) ClientIP(req *http.Request) string {
	return ClientIP(req, h.trusted)
}

func (h pierHost) Routes() []pier.RouteInfo {
	routes := h.r.Routes()
	out := make([]pier.RouteInfo, len(routes))
	for i, ri := range routes {
		out[i] = pier.RouteInfo{Method: ri.Method, Pattern: ri.Pattern, PluginID: ri.PluginID, Middleware: ri.Middleware}
	}
	return out
}

func (h pierHost) Handler(method, pattern string) (http.Handler, bool) {
	return h.r.Handler(method, pattern)
}

func (h pierHost) MountStream(method, path string, handler http.Handler, middleware ...string) error {
	h.r.BindPlugin(pier.PluginID)
	return h.r.MountStream(method, path, handler, middleware...)
}

// MountJSON registers a plain GET route (no middleware) under the pier
// pseudo-plugin; only GET is supported.
func (h pierHost) MountJSON(method, path string, handler http.Handler) error {
	if strings.ToUpper(strings.TrimSpace(method)) != http.MethodGet {
		return fmt.Errorf("surf: pier may mount JSON routes with GET only, got %q", method)
	}
	if owner, ok := h.Owner(http.MethodGet, path); ok {
		return fmt.Errorf("surf: route GET %s (plugin %q) collides with a route the MCP module mounts", path, owner)
	}
	h.r.BindPlugin(pier.PluginID)
	h.r.GroupRaw("", nil, func(g pact.Router) {
		g.Get(path, handler.ServeHTTP)
	})
	return nil
}

func (h pierHost) Owner(method, path string) (string, bool) {
	owner, ok := h.r.seen[strings.ToUpper(strings.TrimSpace(method))+" "+path]
	return owner, ok
}