nvim/lua/debugging.lua

local dap, dapui = require("dap"), require("dapui")

-- Install debug adapters via Mason (same pattern as the LSP tool loop in
-- plugins.lua). codelldb -> c/cpp/rust, debugpy -> python,
-- js-debug-adapter -> node/ts, haskell-debug-adapter -> haskell.
-- java-debug-adapter is installed by the LSP ensure loop and wired through
-- jdtls (see lua/lsp.lua).
-- Note: haskell-debug-adapter builds from source via cabal on first install
-- (needs ghc/cabal on PATH) so it can take a few minutes to appear.
local registry = require("mason-registry")
registry.refresh(function()
    for _, tool in ipairs({ "debugpy", "codelldb", "js-debug-adapter", "haskell-debug-adapter" }) do
        local ok, pkg = pcall(registry.get_package, tool)
        if ok and not pkg:is_installed() then pkg:install() end
    end
end)

dapui.setup()
require("nvim-dap-virtual-text").setup()

-- Auto-wire adapters + default launch configs for every mason-installed
-- adapter. Empty handlers = use mason-nvim-dap's default handler for all.
-- To add a language later: install its adapter in the loop above; it is
-- configured here automatically. Override by defining dap.configurations.<ft>
-- below this call.
require("mason-nvim-dap").setup({
    ensure_installed = {},
    automatic_installation = false,
    handlers = {},
})

-- JS/TS (node): mason-nvim-dap ships no default handler for js-debug-adapter,
-- so wire the pwa-node adapter and launch/attach configs manually.
dap.adapters["pwa-node"] = {
    type = "server",
    host = "localhost",
    port = "${port}",
    executable = {
        command = "node",
        args = {
            vim.fs.joinpath(vim.fn.stdpath("data"), "mason", "packages",
                "js-debug-adapter", "js-debug", "src", "dapDebugServer.js"),
            "${port}",
        },
    },
}
for _, ft in ipairs({ "javascript", "typescript" }) do
    dap.configurations[ft] = {
        {
            type = "pwa-node",
            request = "launch",
            name = "Launch file",
            program = "${file}",
            cwd = "${workspaceFolder}",
        },
        {
            type = "pwa-node",
            request = "attach",
            name = "Attach to process",
            processId = require("dap.utils").pick_process,
            cwd = "${workspaceFolder}",
        },
    }
end

-- Haskell (plain ghc): mason-nvim-dap's default handler auto-wires the
-- haskell-debug-adapter, but its default launch config assumes `stack ghci`
-- (with a literal "TARGET" placeholder). Override it to drive ghci-dap
-- directly so a bare `.hs` file debugs with <F5> — no cabal/stack project
-- required. ghci-dap resolves via PATH (mason bin). Switch ghciCmd to
-- `cabal exec -- ghci-dap ...` or `stack ghci --with-ghc=ghci-dap ...` if you
-- later move to a build tool. Verified end-to-end: loads ${file}, stops at
-- entry, hits breakpoints.
dap.configurations.haskell = {
    {
        type = "haskell",
        request = "launch",
        name = "Debug (ghc)",
        workspace = "${workspaceFolder}",
        startup = "${file}",
        stopOnEntry = true,
        logFile = vim.fs.joinpath(vim.fn.stdpath("data"), "haskell-dap.log"),
        logLevel = "WARNING",
        ghciEnv = vim.empty_dict(),
        ghciPrompt = "H>>= ",
        ghciInitialPrompt = "ghci> ",
        ghciCmd = "ghci-dap --interactive -i${workspaceFolder} ${startup}",
    },
}

-- Run debuggees in dap-ui's Console terminal so programs that read user input
-- work. Without this, nvim-dap uses an output-only internal console with no
-- stdin (the program just hangs on input()/getLine/scanf). dap-ui registers its
-- Console as dap.defaults.fallback.terminal_win_cmd, so any adapter that runs
-- the program in an integrated terminal is routed there. Adapters disagree on
-- the key -- debugpy/pwa-node use `console`, codelldb uses `terminal` -- and
-- each ignores the other, so set both on every launch config. Applies to the
-- mason-auto-generated configs (python/cpp/rust) too, since it runs after their
-- setup. To type: focus the Console window and press `i` (terminal insert).
for _, configs in pairs(dap.configurations) do
    for _, cfg in ipairs(configs) do
        if cfg.request == "launch" then
            if cfg.console == nil then cfg.console = "integratedTerminal" end
            if cfg.terminal == nil then cfg.terminal = "integrated" end
        end
    end
end

-- Open/close the dap-ui panels automatically with the session.
dap.listeners.before.attach.dapui_config           = function() dapui.open() end
dap.listeners.before.launch.dapui_config           = function() dapui.open() end
dap.listeners.before.event_terminated.dapui_config = function() dapui.close() end
dap.listeners.before.event_exited.dapui_config     = function() dapui.close() end

-- VS Code standard F-keys
local map = vim.keymap.set
map("n", "<F5>",     dap.continue,          { desc = "Debug: continue / start" })
map("n", "<S-F5>",   dap.terminate,         { desc = "Debug: stop" })
map("n", "<C-S-F5>", dap.restart,           { desc = "Debug: restart" })
map("n", "<F6>",     dap.pause,             { desc = "Debug: pause" })
map("n", "<F9>",     dap.toggle_breakpoint, { desc = "Debug: toggle breakpoint" })
map("n", "<F10>",    dap.step_over,         { desc = "Debug: step over" })
map("n", "<F11>",    dap.step_into,         { desc = "Debug: step into" })
map("n", "<S-F11>",  dap.step_out,          { desc = "Debug: step out" })

-- Leader maps (preserve the previous <leader>d* bindings + a few niceties;
-- discoverable via <C-k> Pick keymaps thanks to desc).
map("n", "<leader>duo", dapui.open,                  { desc = "Debug: open UI" })
map("n", "<leader>duc", dapui.close,                 { desc = "Debug: close UI" })
map("n", "<leader>dbp", dap.toggle_breakpoint,       { desc = "Debug: toggle breakpoint" })
map("n", "<leader>drc", dap.run_to_cursor,           { desc = "Debug: run to cursor" })
map("n", "<leader>dr",  dap.repl.toggle,             { desc = "Debug: toggle REPL" })
map("n", "<leader>de",  function() dapui.eval() end, { desc = "Debug: eval under cursor" })
map("n", "<leader>dB",  function()
    dap.set_breakpoint(vim.fn.input("Breakpoint condition: "))
end, { desc = "Debug: conditional breakpoint" })