-- repl.lua — readline loop, input dispatch, prompt rendering.
-- Wires ffi/readline + router + executor + broker + context + renderer.
-- See docs/PHASE0.md §5 (dispatch), §9 (prompt + readline).

local rl       = require("ffi.readline")
local router   = require("router")
local executor = require("executor")
local broker   = require("broker")
local renderer = require("renderer")
local Context  = require("context")

local M = {}

local HELP = [[
Meta commands (Phase 0):
  :quit / :q       exit aish
  :clear           clear screen (history kept)
  :reset           clear in-memory conversation history
  :model <name>    switch active model
  :models          list configured models (* = active)
  :history         show conversation turns
  :exec <cmd>      force shell execution
  :ask <text>      force AI query
  :help            this message
]]

function M.run(config)
    assert(config and config.models, "repl.run: config.models required")
    local active_name = config.default_model or next(config.models)
    local active_cfg  = config.models[active_name]
    if not active_cfg then
        error("aish: default_model '" .. tostring(active_name)
              .. "' not found in config.models")
    end

    local ctx = Context.new(config.context or {})

    local function prompt()
        return ("[aish:%s]> "):format(active_name)
    end

    local function status_evictions(n)
        if n and n > 0 then
            renderer.status(("oldest %d turns evicted"):format(n))
        end
    end

    -- Run a shell command, framing output and (per config.shell.capture_output)
    -- injecting it back into context as a `[exec output]`-tagged user turn.
    local function run_shell(cmd)
        local chd, err = executor.maybe_chdir(cmd)
        if chd ~= nil then
            if chd then
                local pwd = io.popen("pwd"):read("*l") or "?"
                renderer.status("cwd -> " .. pwd)
            else
                renderer.status("cd: " .. tostring(err))
            end
            return
        end
        local out, code = executor.exec(cmd)
        renderer.exec_output(out, code)
        if config.shell and config.shell.capture_output then
            ctx:append({ role = "user", content = "[exec output]\n" .. out })
            status_evictions(ctx:enforce_budget())
        end
    end

    -- Send user text to the active model, render the response, and (per
    -- §6 + config.shell.confirm_cmd) optionally execute extracted CMD: lines.
    local function ask_ai(text)
        ctx:append({ role = "user", content = text })
        local resp, err = broker.chat(active_cfg, ctx:to_messages())
        if not resp then
            renderer.status("broker error: " .. tostring(err))
            table.remove(ctx.turns)  -- back out the user turn we just added
            return
        end
        ctx:append({ role = "assistant", content = resp })
        status_evictions(ctx:enforce_budget())
        renderer.assistant(resp)

        for _, cmd in ipairs(executor.extract_cmd_lines(resp)) do
            local doit
            if config.shell and config.shell.confirm_cmd then
                local ans = rl.readline(("execute '%s'? [y/N] "):format(cmd)) or ""
                doit = (ans:lower():sub(1, 1) == "y")
            else
                doit = true
            end
            if doit then run_shell(cmd) end
        end
    end

    -- Meta dispatch table.
    local meta = {
        quit  = function() os.exit(0) end,
        q     = function() os.exit(0) end,
        clear = function() io.write("\27[H\27[2J"); io.flush() end,
        reset = function()
            ctx:reset(); renderer.status("context reset")
        end,
        model = function(args)
            local name = args:match("^%s*(%S+)")
            if not name or not config.models[name] then
                renderer.status("usage: :model <name>; not found: " .. tostring(name))
                return
            end
            active_name, active_cfg = name, config.models[name]
            renderer.status("model -> " .. name)
        end,
        models = function()
            renderer.status(("models (active: %s):"):format(active_name))
            for name, cfg in pairs(config.models) do
                local mark = (name == active_name) and "*" or " "
                io.write(("  %s %-8s  %s @ %s\n"):format(
                    mark, name, cfg.model or "?", cfg.endpoint or "?"))
            end
        end,
        history = function()
            if #ctx.turns == 0 then
                renderer.status("(empty)"); return
            end
            for i, t in ipairs(ctx.turns) do
                io.write(("[%d] %s: %s\n"):format(
                    i, t.role, t.content:gsub("\n", " ")))
            end
        end,
        exec = function(args) run_shell(args) end,
        ask  = function(args) ask_ai(args)    end,
        help = function() io.write(HELP)      end,
    }

    -- Main loop.
    while true do
        local line = rl.readline(prompt())
        if line == nil then          -- EOF (Ctrl-D on empty line)
            io.write("\n"); break
        end
        if line:gsub("%s", "") == "" then
            -- empty / whitespace-only: skip silently
        else
            rl.add_history(line)
            local kind, payload = router.classify(line, config)
            if kind == "meta" then
                local name, rest = payload:match("^(%S+)%s*(.*)$")
                local handler = name and meta[name]
                if handler then
                    handler(rest or "")
                else
                    renderer.status("unknown meta command: :" .. tostring(name))
                end
            elseif kind == "shell" then
                run_shell(payload)
            else  -- "ai"
                ask_ai(payload)
            end
        end
    end
end

-- Phase 0 module export. Meta-command list shown above lives in HELP and
-- is implemented inline in run().
return M