-- main.lua — entry point
-- Phase 0: arg parsing, config load, REPL start.
-- See docs/PHASE0.md §4, §10. -p one-shot mode lands per issue #4.

-- Make project modules and the vendored dkjson resolvable from the repo root.
-- Run aish with the repo root as cwd; PTY-relative resolution lands later.
package.path = "./?.lua;./vendor/?.lua;" .. package.path

local USAGE = [[
aish — AI-augmented conversational shell.

Usage:
  luajit main.lua [--config <path>] [--help]            -- interactive REPL
  luajit main.lua -p "<prompt>" [--config <path>]       -- one-shot, print + exit

In -p mode, if stdin is not a TTY it's read as additional context and
prepended to the prompt as a fenced block — composes with Unix pipes:
  tail app.log | aish -p "any anomalies?"

Config resolution order (PHASE0.md §10):
  1. --config <path>
  2. $AISH_CONFIG
  3. ~/.config/aish/config.lua
  4. ./config.lua
]]

local function parse_args(argv)
    local out = {}
    local i = 1
    while i <= #argv do
        local a = argv[i]
        if a == "--config" then
            out.config = argv[i + 1]
            i = i + 2
        elseif a == "--help" or a == "-h" then
            out.help = true
            i = i + 1
        elseif a == "-p" or a == "--prompt" then
            out.prompt = argv[i + 1]
            if not out.prompt then
                io.stderr:write("aish: -p requires a prompt argument\n")
                os.exit(2)
            end
            i = i + 2
        else
            io.stderr:write("aish: unrecognized argument: " .. a .. "\n")
            os.exit(2)
        end
    end
    return out
end

local function load_config(opts)
    -- --config is explicit: use exactly that path or fail. No silent fallback.
    if opts.config then
        local f = io.open(opts.config, "r")
        if not f then
            error("aish: --config " .. opts.config .. ": cannot open")
        end
        f:close()
        return dofile(opts.config), opts.config
    end

    local home = os.getenv("HOME") or ""
    local candidates = {}
    local function push(p) if p and p ~= "" then candidates[#candidates + 1] = p end end
    push(os.getenv("AISH_CONFIG"))
    push(home .. "/.config/aish/config.lua")
    push("./config.lua")

    for _, path in ipairs(candidates) do
        local f = io.open(path, "r")
        if f then f:close(); return dofile(path), path end
    end
    error("aish: no config.lua found (tried: "
          .. table.concat(candidates, ", ") .. ")")
end

-- One-shot mode: read non-TTY stdin (if any), compose prompt, stream
-- broker reply to stdout, exit. Bypasses repl.lua entirely — no REPL,
-- no MCP, no tool loop, no Norris. The model's reply is printed
-- verbatim (including any "CMD:" lines, which are NOT executed in
-- this mode by design — the user can pipe-grep them as they wish).
local function run_one_shot(config, user_prompt)
    local libc   = require("ffi.libc")
    local broker = require("broker")

    local composed = user_prompt
    if not libc.isatty(0) then
        local piped = io.read("*a") or ""
        if piped ~= "" then
            composed = "```\n" .. piped .. "\n```\n\n" .. user_prompt
        end
    end

    local model_name = config.default_model
    local model_cfg  = config.models and config.models[model_name]
    if not model_cfg then
        io.stderr:write(("aish: default_model '%s' not found in models{}\n")
                        :format(tostring(model_name)))
        os.exit(2)
    end

    local messages = { { role = "user", content = composed } }
    local got_any = false
    local ok, err = broker.chat_stream(model_cfg, messages,
        function(kind, payload)
            if kind == "text" and payload and payload ~= "" then
                io.write(payload); io.flush()
                got_any = true
            end
        end)
    if not ok then
        if got_any then io.write("\n") end
        io.stderr:write("aish: broker error: " .. tostring(err) .. "\n")
        os.exit(1)
    end
    if got_any then io.write("\n") end
end

local function main(argv)
    local opts = parse_args(argv or {})
    if opts.help then io.write(USAGE); return end

    local config, config_path = load_config(opts)
    io.stderr:write(("aish: loaded config from %s\n"):format(config_path))

    if opts.prompt then
        run_one_shot(config, opts.prompt)
        return
    end

    local repl = require("repl")
    repl.run(config)
end

main(arg)