package tools

import (
	"context"
	"fmt"
	"strings"
	"time"

	"github.com/modelcontextprotocol/go-sdk/mcp"

	"isphere-ai-bridge/internal/isphere"
)

const ToolNameReceiveFiles = "isphere_receive_files"

type ReceiveFileDownloadQuery struct {
	FileRef   string
	OutputDir string
	Preview   bool
}

type ReceiveFileDownloadResolution struct {
	Found                bool
	Source               string
	MatchedScore         int
	BlockedReasonCode    string
	BlockedReasonMessage string
}

type ReceiveFileDownloadResolver interface {
	ResolveReceiveFileDownload(context.Context, ReceiveFileDownloadQuery) (ReceiveFileDownloadResolution, error)
}

type receiveFileDownloadResolverFunc func(context.Context, ReceiveFileDownloadQuery) (ReceiveFileDownloadResolution, error)

func (f receiveFileDownloadResolverFunc) ResolveReceiveFileDownload(ctx context.Context, query ReceiveFileDownloadQuery) (ReceiveFileDownloadResolution, error) {
	return f(ctx, query)
}

type ReceiveFilesArgs struct {
	ConversationID   string `json:"conversation_id,omitempty" jsonschema:"conversation id filter for file listing"`
	MessageID        string `json:"message_id,omitempty" jsonschema:"message id filter for file listing"`
	FileID           string `json:"file_id,omitempty" jsonschema:"file id filter for file listing"`
	FileRef          string `json:"file_ref,omitempty" jsonschema:"download file reference; defaults to file_id when omitted"`
	NameContains     string `json:"name_contains,omitempty" jsonschema:"case-insensitive filename substring filter"`
	Mode             string `json:"mode,omitempty" jsonschema:"file receive mode; C14 supports list only"`
	OutputDir        string `json:"output_dir,omitempty" jsonschema:"download output directory; not accepted in current list-only mode"`
	Cursor           string `json:"cursor,omitempty" jsonschema:"pagination cursor; currently only empty cursor is supported"`
	SourcePreference string `json:"source_preference,omitempty" jsonschema:"source selector; currently supports auto or local_readonly only"`
	Preview          bool   `json:"preview,omitempty" jsonschema:"accepted for contract compatibility in list mode"`
	Limit            int    `json:"limit,omitempty" jsonschema:"maximum number of files to return; zero or negative returns all matches"`
}

func RegisterISphereFileTools(server *mcp.Server, source ReceiveMessagesSource) {
	RegisterISphereFileToolsWithDownloadResolver(server, source, nil)
}

func RegisterISphereFileToolsWithDownloadResolver(server *mcp.Server, source ReceiveMessagesSource, downloadResolver ReceiveFileDownloadResolver) {
	if source == nil {
		source = isphere.EncryptedPacketLogSource{}
	}

	mcp.AddTool[ReceiveFilesArgs, map[string]any](server, &mcp.Tool{
		Name:        ToolNameReceiveFiles,
		Description: "List iSphere file metadata candidates from the configured read-only message source; download preview returns structured blocked/planned status until cache mapping is validated.",
	}, func(ctx context.Context, _ *mcp.CallToolRequest, input ReceiveFilesArgs) (*mcp.CallToolResult, map[string]any, error) {
		started := time.Now().UTC()
		mode := strings.ToLower(strings.TrimSpace(input.Mode))
		if mode == "" {
			mode = "list"
		}
		if mode != "list" && mode != "download" {
			return nil, nil, fmt.Errorf("isphere_receive_files mode %q is not available; supported modes are list and download preview", input.Mode)
		}
		if err := validateLocalReadonlySourceAndCursor(ToolNameReceiveFiles, input.SourcePreference, input.Cursor); err != nil {
			return nil, nil, err
		}
		if mode == "download" {
			return nil, receiveFileDownloadPreviewResult(ctx, input, downloadResolver, started), nil
		}
		if strings.TrimSpace(input.OutputDir) != "" {
			return nil, nil, fmt.Errorf("isphere_receive_files output_dir is only available for download mode")
		}
		messages, err := source.ReceiveMessages(ctx, isphere.ReceiveMessagesQuery{Limit: 0})
		if err != nil {
			return nil, nil, err
		}
		files := isphere.ListFilesFromMessages(messages.Messages, isphere.ListFilesQuery{
			ConversationID: input.ConversationID,
			MessageID:      input.MessageID,
			FileID:         input.FileID,
			NameContains:   input.NameContains,
			Limit:          input.Limit,
		})
		return nil, receiveFilesResultToMap(files, started, time.Now().UTC()), nil
	})
}

func receiveFileDownloadPreviewResult(ctx context.Context, input ReceiveFilesArgs, resolver ReceiveFileDownloadResolver, started time.Time) map[string]any {
	fileRef := strings.TrimSpace(input.FileRef)
	if fileRef == "" {
		fileRef = strings.TrimSpace(input.FileID)
	}
	if fileRef == "" {
		return receiveFileDownloadBlockedResult(fileRef, "file_ref_required", "download preview requires file_ref or file_id", started, time.Now().UTC())
	}
	if !input.Preview {
		return receiveFileDownloadBlockedResult(fileRef, "file_download_production_disabled", "real file download is blocked; pass preview=true for a no-copy plan", started, time.Now().UTC())
	}
	if resolver == nil {
		return receiveFileDownloadBlockedResult(fileRef, "file_cache_mapping_missing", "no accepted receive-file cache mapping is configured", started, time.Now().UTC())
	}
	resolution, err := resolver.ResolveReceiveFileDownload(ctx, ReceiveFileDownloadQuery{
		FileRef:   fileRef,
		OutputDir: strings.TrimSpace(input.OutputDir),
		Preview:   true,
	})
	if err != nil {
		return receiveFileDownloadBlockedResult(fileRef, "file_cache_mapping_error", err.Error(), started, time.Now().UTC())
	}
	if !resolution.Found {
		code := strings.TrimSpace(resolution.BlockedReasonCode)
		if code == "" {
			code = "file_cache_mapping_missing"
		}
		message := strings.TrimSpace(resolution.BlockedReasonMessage)
		if message == "" {
			message = "no accepted receive-file cache mapping matched the requested file_ref"
		}
		return receiveFileDownloadBlockedResult(fileRef, code, message, started, time.Now().UTC())
	}
	return map[string]any{
		"ok":                      true,
		"mode":                    "download",
		"download_status":         "planned",
		"file_ref":                fileRef,
		"output_dir_requested":    strings.TrimSpace(input.OutputDir) != "",
		"mapping_source":          resolution.Source,
		"matched_score":           resolution.MatchedScore,
		"preview":                 true,
		"file_contents_read":      false,
		"file_copied":             false,
		"real_download_attempted": false,
		"raw_paths_returned":      false,
		"audit":                   receiveFileDownloadAudit("planned", started, time.Now().UTC()),
	}
}

func receiveFileDownloadBlockedResult(fileRef string, reasonCode string, reasonMessage string, started time.Time, finished time.Time) map[string]any {
	return map[string]any{
		"ok":                      false,
		"mode":                    "download",
		"download_status":         "blocked",
		"blocked_reason_code":     reasonCode,
		"blocked_reason_message":  reasonMessage,
		"file_ref":                fileRef,
		"preview":                 true,
		"file_contents_read":      false,
		"file_copied":             false,
		"real_download_attempted": false,
		"raw_paths_returned":      false,
		"audit":                   receiveFileDownloadAudit("blocked", started, finished),
	}
}

func receiveFileDownloadAudit(result string, started time.Time, finished time.Time) map[string]any {
	return map[string]any{
		"tool":           ToolNameReceiveFiles,
		"source":         "local_readonly",
		"execution_mode": "download_preview",
		"started_at":     started.Format(time.RFC3339Nano),
		"finished_at":    finished.Format(time.RFC3339Nano),
		"result":         result,
	}
}

func receiveFilesResultToMap(result isphere.ListFilesResult, started time.Time, finished time.Time) map[string]any {
	files := make([]map[string]any, 0, len(result.Files))
	for _, file := range result.Files {
		files = append(files, map[string]any{
			"file_id":         file.FileID,
			"message_id":      nullableString(file.MessageID),
			"conversation_id": nullableString(file.ConversationID),
			"file_name":       file.FileName,
			"size_bytes":      file.SizeBytes,
			"mime_type":       file.MimeType,
			"created_at":      nullableString(file.CreatedAt),
			"download_ref":    nullableString(file.DownloadRef),
			"saved_path":      nullableString(file.SavedPath),
			"sha256":          nullableString(file.SHA256),
			"source":          file.Source,
			"raw_ref":         file.RawRef,
		})
	}
	return map[string]any{
		"ok":          true,
		"mode":        "list",
		"files":       files,
		"next_cursor": nil,
		"audit": map[string]any{
			"tool":           ToolNameReceiveFiles,
			"source":         "local_readonly",
			"execution_mode": "read",
			"started_at":     started.Format(time.RFC3339Nano),
			"finished_at":    finished.Format(time.RFC3339Nano),
			"result":         "ok",
		},
	}
}

func nullableString(value string) any {
	if strings.TrimSpace(value) == "" {
		return nil
	}
	return value
}