-- main.lua — entry point
-- Phase 0: arg parsing, config load, REPL start.
-- See docs/PHASE0.md §4, §10.

-- 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]

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
        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

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))

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

main(arg)