// Package connector provides the "search" and "fetch" tools expected by
// ChatGPT-style MCP connectors (https://platform.openai.com/docs/mcp), on
// top of the same Gitea SDK calls the search and file domains already use.
package connector

import (
	"context"
	"encoding/base64"
	"fmt"

	"gitea.com/gitea/gitea-mcp/pkg/annotation"
	"gitea.com/gitea/gitea-mcp/pkg/gitea"
	"gitea.com/gitea/gitea-mcp/pkg/params"
	"gitea.com/gitea/gitea-mcp/pkg/to"
	"gitea.com/gitea/gitea-mcp/pkg/tool"

	gitea_sdk "gitea.dev/sdk"
	"github.com/modelcontextprotocol/go-sdk/mcp"
)

// Tool holds the connector tools (scope "connector"): search and fetch.
var Tool = tool.New("connector")

const (
	SearchToolName = "search"
	FetchToolName  = "fetch"
)

var (
	SearchTool = tool.NewDefinition(
		SearchToolName,
		"Search Gitea repositories by keyword. Returns concise entries suitable for ChatGPT-style connectors.",
		annotation.ReadOnly("Search"),
		tool.String("query", tool.Required(), tool.Description("search keyword")),
		tool.String("owner", tool.Description("filter results to repositories owned by this user")),
		tool.String("org", tool.Description("filter results to repositories owned by this organization")),
		tool.Number("page", tool.Description(params.PageDesc), tool.Default(1)),
		tool.Number("per_page", tool.Description(params.PaginationDesc), tool.Default(30)),
	)

	FetchTool = tool.NewDefinition(
		FetchToolName,
		"Fetch a file's decoded content and metadata from a Gitea repository. Suitable for ChatGPT-style connectors.",
		annotation.ReadOnly("Fetch"),
		tool.String("owner", tool.Required(), tool.Description(params.OwnerDesc)),
		tool.String("repo", tool.Required(), tool.Description(params.RepoDesc)),
		tool.String("path", tool.Required()),
		tool.String("ref", tool.Description("branch, tag, or commit SHA")),
	)
)

func init() {
	Tool.RegisterRead(tool.ServerTool{
		Tool:    SearchTool,
		Handler: SearchFn,
	})
	Tool.RegisterRead(tool.ServerTool{
		Tool:    FetchTool,
		Handler: FetchFn,
	})
}

// SearchFn searches Gitea repositories by keyword, optionally scoped to an
// owner or organization, and returns concise entries.
func SearchFn(ctx context.Context, args map[string]any) (*mcp.CallToolResult, error) {
	query, err := params.GetString(args, "query")
	if err != nil {
		return to.ErrorResult(err)
	}
	client, err := gitea.ClientFromContext(ctx)
	if err != nil {
		return to.ErrorResult(fmt.Errorf("get gitea client err: %v", err))
	}

	ownerName := params.GetOptionalString(args, "owner", "")
	if ownerName == "" {
		ownerName = params.GetOptionalString(args, "org", "")
	}
	var ownerID int64
	if ownerName != "" {
		owner, _, err := client.Users.GetUserInfo(ctx, ownerName)
		if err != nil {
			return to.ErrorResult(fmt.Errorf("resolve owner %q err: %v", ownerName, err))
		}
		ownerID = owner.ID
	}

	page, pageSize := params.GetPagination(args, 30)
	opt := gitea_sdk.SearchRepoOptions{
		Keyword: query,
		OwnerID: ownerID,
		ListOptions: gitea_sdk.ListOptions{
			Page:     page,
			PageSize: pageSize,
		},
	}
	repos, _, err := client.Repositories.SearchRepos(ctx, opt)
	if err != nil {
		return to.ErrorResult(fmt.Errorf("search repos err: %v", err))
	}
	return to.TextResult(slimSearchResults(repos))
}

// FetchFn fetches a file's content and decodes it, returning the decoded
// content alongside path, sha, size, and encoding metadata.
func FetchFn(ctx context.Context, args map[string]any) (*mcp.CallToolResult, error) {
	owner, err := params.GetString(args, "owner")
	if err != nil {
		return to.ErrorResult(err)
	}
	repo, err := params.GetString(args, "repo")
	if err != nil {
		return to.ErrorResult(err)
	}
	filePath, err := params.GetString(args, "path")
	if err != nil {
		return to.ErrorResult(err)
	}
	ref := params.GetOptionalString(args, "ref", "")

	client, err := gitea.ClientFromContext(ctx)
	if err != nil {
		return to.ErrorResult(fmt.Errorf("get gitea client err: %v", err))
	}
	content, _, err := client.Repositories.GetContents(ctx, owner, repo, ref, filePath)
	if err != nil {
		return to.ErrorResult(fmt.Errorf("get file err: %v", err))
	}

	decoded, err := decodeContent(content)
	if err != nil {
		return to.ErrorResult(err)
	}
	return to.TextResult(map[string]any{
		"path":     content.Path,
		"sha":      content.SHA,
		"size":     content.Size,
		"encoding": stringOrEmpty(content.Encoding),
		"content":  decoded,
	})
}

func decodeContent(c *gitea_sdk.ContentsResponse) (string, error) {
	if c.Content == nil {
		return "", nil
	}
	raw, err := base64.StdEncoding.DecodeString(*c.Content)
	if err != nil {
		return "", fmt.Errorf("decode base64 content err: %v", err)
	}
	return string(raw), nil
}

func stringOrEmpty(s *string) string {
	if s == nil {
		return ""
	}
	return *s
}