local dap = require("dap")

local M = {}

-- Locate the delve binary (prefer mason, fall back to PATH).
local function dlv_command()
    local mason = vim.fn.expand("$HOME/.local/share/nvim/mason/bin/dlv")
    if vim.fn.filereadable(mason) == 1 then
        return mason
    end
    return "dlv"
end

-- Adapter: run delve in DAP server mode on a free port.
dap.adapters.go = {
    type = "server",
    port = "${port}",
    executable = {
        command = dlv_command(),
        args = { "dap", "-l", "127.0.0.1:${port}" },
    },
}

-- Configurations
dap.configurations.go = {
    {
        type = "go",
        request = "launch",
        name = "Debug (current file)",
        program = "${file}",
    },
    {
        type = "go",
        request = "launch",
        name = "Debug package",
        program = "${fileDirname}",
    },
    {
        type = "go",
        request = "launch",
        name = "Debug package (with args)",
        program = "${fileDirname}",
        args = function()
            local input = vim.fn.input("Args: ")
            return vim.split(input, " ", { trimempty = true })
        end,
    },
    {
        type = "go",
        request = "launch",
        mode = "test",
        name = "Debug test (current file)",
        program = "${file}",
    },
    {
        type = "go",
        request = "launch",
        mode = "test",
        name = "Debug test (package)",
        program = "${fileDirname}",
    },
    {
        type = "go",
        request = "attach",
        mode = "local",
        name = "Attach to process",
        processId = require("dap.utils").pick_process,
    },
}

-- Debug the test function under the cursor using delve's -test.run filter.
local function debug_test_at_cursor()
    local ok, node = pcall(vim.treesitter.get_node)
    if not ok or not node then
        vim.notify("Tree-sitter parser not found. Ensure you are in a Go buffer.", vim.log.levels.ERROR)
        return
    end

    local func_name = nil
    local attempts = 0
    while node do
        if node:type() == "function_declaration" then
            for child in node:iter_children() do
                if child:type() == "identifier" then
                    func_name = vim.treesitter.get_node_text(child, 0)
                    break
                end
            end
            break
        end
        node = node:parent()
        attempts = attempts + 1
        if attempts > 50 then
            break
        end
    end

    if not func_name then
        vim.notify("Cursor is not inside a test function.", vim.log.levels.WARN)
        return
    end

    dap.run({
        type = "go",
        request = "launch",
        mode = "test",
        name = "Debug test: " .. func_name,
        program = "${fileDirname}",
        args = { "-test.run", "^" .. func_name .. "$" },
    })
end

M.debug_test_at_cursor = debug_test_at_cursor

return M