local log = require("log")
local repo = require("git.repo")

local M = {}

---@param opts { amend: boolean? }?
function M.commit(opts)
    local amend = opts and opts.amend or false
    local gitdir, worktree = repo.resolve_cwd()
    if not gitdir or not worktree then
        log.warning("not in a git repository")
        return
    end
    local msg_path = vim.fs.joinpath(gitdir, "COMMIT_EDITMSG")

    local initial = ""
    if amend then
        local result = vim.system(
            { "git", "log", "-1", "--pretty=%B" },
            { cwd = worktree, text = true }
        ):wait()
        if result.code == 0 then
            initial = (result.stdout or ""):gsub("\n+$", "")
        else
            log.warning("git log -1 failed: %s", vim.trim(result.stderr or ""))
        end
    end

    local f, err = io.open(msg_path, "w")
    if not f then
        log.error("failed to open %s: %s", msg_path, err or "")
        return
    end
    f:write(initial)
    f:close()

    local ok, err = pcall(vim.cmd.edit, vim.fn.fnameescape(msg_path))
    if not ok then
        log.error("failed to open %s: %s", msg_path, err or "")
        return
    end
    local buf = vim.api.nvim_get_current_buf()
    if vim.api.nvim_buf_get_name(buf) ~= msg_path then
        -- `:edit` returned without surfacing an error but didn't actually
        -- switch (defensive against an unusual ftplugin/autocmd path). Bail
        -- before attaching a BufWriteCmd that would overwrite the wrong
        -- file on the next `:w`.
        log.error("failed to switch to %s", msg_path)
        return
    end
    vim.bo[buf].filetype = "gitcommit"

    vim.api.nvim_create_autocmd("BufWriteCmd", {
        buffer = buf,
        callback = function()
            local lines = vim.api.nvim_buf_get_lines(buf, 0, -1, false)
            local fw, werr = io.open(msg_path, "w")
            if not fw then
                log.error("failed to write %s: %s", msg_path, werr or "")
                return
            end
            fw:write(table.concat(lines, "\n"))
            fw:close()
            vim.bo[buf].modified = false

            local cmd = { "git", "commit", "-F", msg_path }
            if amend then
                table.insert(cmd, "--amend")
            end
            local result = vim.system(cmd, { cwd = worktree, text = true })
                :wait()
            if result.code ~= 0 then
                log.error(
                    "git commit failed: %s",
                    vim.trim(result.stderr or "")
                )
                return
            end
            local out = vim.trim(result.stdout or "")
            if out ~= "" then
                log.info("%s", out)
            end
            vim.api.nvim_buf_delete(buf, { force = true })
        end,
    })
end

return M