// Copyright 2024 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package server

import (
	"context"
	"fmt"
	"net"
	"net/http"
	"strconv"
	"time"

	"github.com/go-chi/chi/v5"
	"github.com/go-chi/chi/v5/middleware"
	"github.com/googleapis/genai-toolbox/internal/sources"
	"github.com/googleapis/genai-toolbox/internal/tools"
)

// Server contains info for running an instance of Toolbox. Should be instantiated with NewServer().
type Server struct {
	conf Config
	root chi.Router

	sources  map[string]sources.Source
	tools    map[string]tools.Tool
	toolsets map[string]tools.Toolset
}

// NewServer returns a Server object based on provided Config.
func NewServer(cfg Config) (*Server, error) {
	r := chi.NewRouter()
	r.Use(middleware.Logger)
	r.Use(middleware.Recoverer)

	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
		_, _ = w.Write([]byte("🧰 Hello world! 🧰"))
	})

	// initalize and validate the sources
	sourcesMap := make(map[string]sources.Source)
	for name, sc := range cfg.SourceConfigs {
		s, err := sc.Initialize()
		if err != nil {
			return nil, fmt.Errorf("unable to initialize source %q: %w", name, err)
		}
		sourcesMap[name] = s
	}
	fmt.Printf("Initalized %d sources.\n", len(sourcesMap))

	// initalize and validate the tools
	toolsMap := make(map[string]tools.Tool)
	for name, tc := range cfg.ToolConfigs {
		t, err := tc.Initialize(sourcesMap)
		if err != nil {
			return nil, fmt.Errorf("unable to initialize tool %q: %w", name, err)
		}
		toolsMap[name] = t
	}
	fmt.Printf("Initalized %d tools.\n", len(toolsMap))

	// create a default toolset that contains all tools
	allToolNames := make([]string, 0, len(toolsMap))
	for name := range toolsMap {
		allToolNames = append(allToolNames, name)
	}
	if cfg.ToolsetConfigs == nil {
		cfg.ToolsetConfigs = make(tools.ToolsetConfigs)
	}
	cfg.ToolsetConfigs[""] = tools.ToolsetConfig{Name: "", ToolNames: allToolNames}
	// initalize and validate the toolsets
	toolsetsMap := make(map[string]tools.Toolset)
	for name, tc := range cfg.ToolsetConfigs {
		t, err := tc.Initialize(cfg.Version, toolsMap)
		if err != nil {
			return nil, fmt.Errorf("unable to initialize toolset %q: %w", name, err)
		}
		toolsetsMap[name] = t
	}
	fmt.Printf("Initalized %d toolsets.\n", len(toolsetsMap))

	s := &Server{
		conf:     cfg,
		root:     r,
		sources:  sourcesMap,
		tools:    toolsMap,
		toolsets: toolsetsMap,
	}

	if router, err := apiRouter(s); err != nil {
		return nil, err
	} else {
		r.Mount("/api", router)
	}

	return s, nil
}

// ListenAndServe starts an HTTP server for the given Server instance.
func (s *Server) ListenAndServe(ctx context.Context) error {
	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	addr := net.JoinHostPort(s.conf.Address, strconv.Itoa(s.conf.Port))
	lc := net.ListenConfig{KeepAlive: 30 * time.Second}
	l, err := lc.Listen(ctx, "tcp", addr)
	if err != nil {
		return fmt.Errorf("failed to open listener for %q: %w", addr, err)
	}

	return http.Serve(l, s.root)
}