// Copyright 2025 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 firestoregetdocuments

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

	firestoreapi "cloud.google.com/go/firestore"
	yaml "github.com/goccy/go-yaml"
	"github.com/googleapis/mcp-toolbox/internal/tools"
	fsUtil "github.com/googleapis/mcp-toolbox/internal/tools/firestore/util"
	"github.com/googleapis/mcp-toolbox/internal/util"
	"github.com/googleapis/mcp-toolbox/internal/util/parameters"
)

const resourceType string = "firestore-get-documents"
const documentPathsKey string = "documentPaths"

func init() {
	if !tools.Register(resourceType, newConfig) {
		panic(fmt.Sprintf("tool type %q already registered", resourceType))
	}
}

func newConfig(ctx context.Context, name string, decoder *yaml.Decoder) (tools.ToolConfig, error) {
	actual := Config{ConfigBase: tools.ConfigBase{Name: name}}
	if err := decoder.DecodeContext(ctx, &actual); err != nil {
		return nil, err
	}
	return actual, nil
}

type compatibleSource interface {
	FirestoreClient() *firestoreapi.Client
	GetDocuments(context.Context, []string) ([]any, error)
}

type Config struct {
	tools.ConfigBase `yaml:",inline"`
	Type             string                 `yaml:"type" validate:"required"`
	Source           string                 `yaml:"source" validate:"required"`
	Annotations      *tools.ToolAnnotations `yaml:"annotations,omitempty"`
}

// validate interface
var _ tools.ToolConfig = Config{}

func (cfg Config) ToolConfigType() string {
	return resourceType
}

func (cfg Config) Initialize(context.Context) (tools.Tool, error) {
	if cfg.Description == "" {
		return nil, fmt.Errorf("description is required for tool %q", cfg.Name)
	}

	documentPathsParameter := parameters.NewArrayParameter(documentPathsKey, "Array of relative document paths to retrieve from Firestore (e.g., 'users/userId' or 'users/userId/posts/postId'). Note: These are relative paths, NOT absolute paths like 'projects/{project_id}/databases/{database_id}/documents/...'", parameters.NewStringParameter("item", "Relative document path"))
	params := parameters.Parameters{documentPathsParameter}

	return Tool{
		BaseTool: tools.NewBaseTool(
			cfg,
			tools.GetAnnotationsOrDefault(cfg.Annotations, tools.NewReadOnlyAnnotations),
			tools.Manifest{Description: cfg.Description, Parameters: params.Manifest(), AuthRequired: cfg.AuthRequired},
			params,
		),
	}, nil
}

// validate interface
var _ tools.Tool = Tool{}

type Tool struct {
	tools.BaseTool[Config]
}

func (t Tool) ToConfig() tools.ToolConfig {
	return t.Cfg
}

func (t Tool) Invoke(ctx context.Context, resourceMgr tools.SourceProvider, params parameters.ParamValues, accessToken tools.AccessToken) (any, util.ToolboxError) {
	source, err := tools.GetCompatibleSource[compatibleSource](resourceMgr, t.Cfg.Source, t.Cfg.Name, t.Cfg.Type)
	if err != nil {
		return nil, util.NewClientServerError("source used is not compatible with the tool", http.StatusInternalServerError, err)
	}

	mapParams := params.AsMap()
	documentPathsRaw, ok := mapParams[documentPathsKey].([]any)
	if !ok {
		return nil, util.NewAgentError(fmt.Sprintf("invalid or missing '%s' parameter; expected an array", documentPathsKey), nil)
	}

	if len(documentPathsRaw) == 0 {
		return nil, util.NewAgentError(fmt.Sprintf("'%s' parameter cannot be empty", documentPathsKey), nil)
	}

	// Use ConvertAnySliceToTyped to convert the slice
	typedSlice, err := parameters.ConvertAnySliceToTyped(documentPathsRaw, "string")
	if err != nil {
		return nil, util.NewAgentError(fmt.Sprintf("failed to convert document paths: %v", err), err)
	}

	documentPaths, ok := typedSlice.([]string)
	if !ok {
		return nil, util.NewAgentError("unexpected type conversion error for document paths", nil)
	}

	// Validate each document path
	for i, path := range documentPaths {
		if err := fsUtil.ValidateDocumentPath(path); err != nil {
			return nil, util.NewAgentError(fmt.Sprintf("invalid document path at index %d: %v", i, err), err)
		}
	}
	resp, err := source.GetDocuments(ctx, documentPaths)
	if err != nil {
		return nil, util.ProcessGcpError(err)
	}
	return resp, nil
}