-- renderer.lua — output formatting and ANSI sequences.
-- Phase 0: assistant text plain-printed with `CMD: ` lines highlighted;
-- exec output framed with the exit code on the closing rule.
-- Phase 1: assistant_delta + assistant_flush for streaming render. CMD:
-- highlighting in streaming mode is deferred (Q12); deltas print raw, the
-- §6 substrate `CMD: ` line is still extractable by executor afterwards.
-- Syntax highlighting hooks land in Phase 6 (was Phase 5 pre-MCP renumber).

local M = {}

local A = {
    reset = "\27[0m",
    bold  = "\27[1m",
    dim   = "\27[2m",
    cyan  = "\27[36m",
    red   = "\27[31m",
}

local function emit(...) io.write(...); io.flush() end

-- Print assistant response text. Lines beginning with `CMD: ` (per the §3
-- substrate-locked extraction marker) are emitted bold+cyan so the user
-- can spot the suggestion without scanning prose.
function M.assistant(text)
    for line in ((text or "") .. "\n"):gmatch("([^\n]*)\n") do
        if line:sub(1, 5) == "CMD: " then
            emit(A.bold, A.cyan, line, A.reset, "\n")
        else
            emit(line, "\n")
        end
    end
end

-- Phase 1: executor.exec streams output live to stdout (PTY multiplex), so
-- the frame is split — exec_begin before the spawn, exec_end after wait().
-- The body is not re-rendered here; live output lands directly between the
-- two rules.
function M.exec_begin()
    emit(A.dim, "─── exec output ───", A.reset, "\n")
end

function M.exec_end(exit_code)
    if exit_code and exit_code ~= 0 then
        emit(A.dim, "─── exit ", A.reset,
             A.red, tostring(exit_code), A.reset,
             A.dim, " ───", A.reset, "\n")
    else
        emit(A.dim, "─── exit 0 ───", A.reset, "\n")
    end
end

-- Single-line dim status (e.g. §8 eviction notice, model switch confirms).
function M.status(line)
    emit(A.dim, "[aish] ", tostring(line), A.reset, "\n")
end

-- Streaming assistant output. Phase 1: deltas are written raw — the §6 CMD:
-- highlighting from M.assistant() is not applied incrementally because
-- mid-line cursor manipulation isn't worth the complexity for Phase 1.
-- Q12 (PHASE1.md §10) tracks the upgrade. The full assistant text is still
-- captured by repl.lua and CMD: extraction works against the reassembled
-- string after the stream ends.

local stream_buf = nil   -- non-nil while a stream is in progress

function M.assistant_delta(chunk)
    if not chunk or chunk == "" then return end
    if stream_buf == nil then stream_buf = "" end
    stream_buf = stream_buf .. chunk
    emit(chunk)
end

function M.assistant_flush()
    if stream_buf == nil then return end
    if not stream_buf:match("\n$") then emit("\n") end
    stream_buf = nil
end

-- Phase 2: MCP tool-call frame. Visual parity with the exec_begin/exec_end
-- frame so the user reads tool dispatch and shell dispatch the same way.
-- tool_call_begin renders the top rule + (optionally) the args as a dim
-- preview; tool_call_end renders the result content followed by a status
-- rule. Status is "ok" (dim) by default; "error" (red) if is_error is true.
-- See docs/PHASE2.md §3 renderer.lua row + §4 Tool invocation.

function M.tool_call_begin(name, args)
    emit(A.dim, "─── tool: ", A.reset,
         A.cyan, name, A.reset,
         A.dim, " ───", A.reset, "\n")
    if args and args ~= "" and args ~= "{}" then
        local shown = (#args <= 200) and args or (args:sub(1, 197) .. "...")
        emit(A.dim, shown, A.reset, "\n")
    end
end

function M.tool_call_end(content, is_error)
    if content and content ~= "" then
        emit(content)
        if not content:match("\n$") then emit("\n") end
    end
    if is_error then
        emit(A.dim, "─── ", A.reset,
             A.red, "error", A.reset,
             A.dim, " ───", A.reset, "\n")
    else
        emit(A.dim, "─── ok ───", A.reset, "\n")
    end
end

-- Phase 3: Norris autonomous mode frames. Banner-style on enter/exit,
-- step counter per iteration, red HALT banner when the destructive-op
-- gate fires. The interactive prompt also gets a ⚡ marker when Norris
-- is active (handled in repl.lua's prompt() function per PHASE0.md §9).
-- See docs/PHASE3.md §3 renderer row.

function M.norris_begin(goal)
    emit(A.bold, A.cyan, "─── NORRIS MODE ─────────────────────────",
         A.reset, "\n")
    if goal and goal ~= "" then
        emit(A.dim, "  goal: ", A.reset, goal, "\n")
    end
    emit(A.bold, A.cyan, "─────────────────────────────────────────",
         A.reset, "\n")
end

function M.norris_step(n, max_n, descr)
    emit(A.dim, ("  ─ step %d/%d ─ "):format(n, max_n), A.reset)
    if descr and descr ~= "" then emit(A.dim, descr, A.reset) end
    emit("\n")
end

function M.norris_halt(step_n, max_n, reason, action)
    emit(A.bold, A.red, "─── NORRIS HALT ──────────────────────────",
         A.reset, "\n")
    emit(A.dim, "  step:   ", A.reset, ("%d/%d"):format(step_n, max_n), "\n")
    emit(A.dim, "  reason: ", A.reset, A.red, tostring(reason), A.reset, "\n")
    -- action may be a long string (command line or JSON-serialized tool call);
    -- truncate at 400 chars to keep the banner readable
    local act = tostring(action or ""):gsub("\n", " ")
    if #act > 400 then act = act:sub(1, 397) .. "..." end
    emit(A.dim, "  action: ", A.reset, act, "\n")
    emit(A.bold, A.red, "──────────────────────────────────────────",
         A.reset, "\n")
end

-- Norris loop exit. status ∈ {"done", "aborted", "budget_exhausted",
--                              "stalled", "broker_error"}.
function M.norris_end(status, reason)
    local color = (status == "done") and A.cyan or A.red
    local label = status:upper():gsub("_", " ")
    emit(A.bold, color, "─── NORRIS ", label, " ──",
         (" "):rep(math.max(0, 28 - #label)),
         A.reset, "\n")
    if reason and reason ~= "" then
        emit(A.dim, "  ", reason, A.reset, "\n")
    end
    emit(A.bold, color, "──────────────────────────────────────────",
         A.reset, "\n")
end

return M