package main

import (
	"context"
	"encoding/json"

	"github.com/mark3labs/mcp-go/mcp"

	"fn-registry/registry"
)

type proposalArgs struct {
	ID     string `json:"id,omitempty"`
	Kind   string `json:"kind,omitempty"`
	Status string `json:"status,omitempty"`
	Limit  int    `json:"limit,omitempty"`
}

func proposalTool() mcp.Tool {
	return mcp.NewTool("fn_proposal",
		mcp.WithDescription("Read proposals from registry.db. With `id`, returns that proposal in full (including evidence). Without `id`, lists proposals filtered by `kind`/`status`, ordered by created_at DESC. Replaces `sqlite3 registry.db \"SELECT ... FROM proposals\"` inline queries."),
		mcp.WithString("id",
			mcp.Description("Proposal ID. If set, ignores kind/status filters and returns single record."),
		),
		mcp.WithString("kind",
			mcp.Description("Filter by kind: new_function, new_type, improve_function, improve_type, new_pipeline."),
			mcp.Enum("new_function", "new_type", "improve_function", "improve_type", "new_pipeline"),
		),
		mcp.WithString("status",
			mcp.Description("Filter by status: pending, approved, rejected, implemented."),
			mcp.Enum("pending", "approved", "rejected", "implemented"),
		),
		mcp.WithNumber("limit",
			mcp.Description("Max rows returned (default 100)."),
			mcp.Min(1),
			mcp.Max(1000),
		),
	)
}

func (d *deps) handleProposal(ctx context.Context, _ mcp.CallToolRequest, args proposalArgs) (*mcp.CallToolResult, error) {
	if args.ID != "" {
		p, err := d.db.GetProposal(args.ID)
		if err != nil {
			return mcp.NewToolResultError("proposal not found: " + args.ID), nil
		}
		b, _ := json.MarshalIndent(p, "", "  ")
		return mcp.NewToolResultText(string(b)), nil
	}

	limit := args.Limit
	if limit <= 0 {
		limit = 100
	}

	ps, err := d.db.ListProposals(registry.ProposalKind(args.Kind), registry.ProposalStatus(args.Status))
	if err != nil {
		return mcp.NewToolResultError("list proposals: " + err.Error()), nil
	}

	if len(ps) > limit {
		ps = ps[:limit]
	}

	out := map[string]any{
		"count":     len(ps),
		"limit":     limit,
		"kind":      args.Kind,
		"status":    args.Status,
		"proposals": ps,
	}
	b, _ := json.MarshalIndent(out, "", "  ")
	return mcp.NewToolResultText(string(b)), nil
}