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

local M = {}

---@class ow.Git.Statusline.Status
---@field head string?
---@field entries ow.Git.Status.Entry[]
---@field unstaged boolean
---@field staged boolean
---@field conflict boolean

---@param entries ow.Git.Status.Entry[]
---@param head string?
---@return ow.Git.Statusline.Status
local function build(entries, head)
    local out = {
        head = head,
        entries = entries,
        unstaged = false,
        staged = false,
        conflict = false,
    }
    for _, e in ipairs(entries) do
        if e.kind == "unstaged" or e.kind == "untracked" then
            out.unstaged = true
        elseif e.kind == "staged" then
            out.staged = true
        elseif e.kind == "unmerged" then
            out.conflict = true
        end
    end
    return out
end

---@param entries ow.Git.Status.Entry[]
---@return string
local function render(entries)
    if #entries == 0 then
        return ""
    end
    local parts = {}
    for _, e in ipairs(entries) do
        table.insert(parts, string.format("%%#%s#%s%%*", e.hl, e.char))
    end
    return table.concat(parts, " ")
end

---@param buf integer
local function clear(buf)
    vim.b[buf].git_status = nil
    vim.b[buf].git_status_string = nil
end

---@param buf integer
---@param r ow.Git.Repo?
local function update_buf(buf, r)
    if not vim.api.nvim_buf_is_valid(buf) then
        return
    end
    local name = vim.api.nvim_buf_get_name(buf)
    if name == "" or util.is_uri(name) then
        return clear(buf)
    end
    r = r or repo.find(buf)
    if not r then
        return clear(buf)
    end
    local rel = vim.fs.relpath(r.worktree, vim.fn.resolve(name))
    if not rel then
        return clear(buf)
    end
    local entries = r.status.entries[rel] or {}
    vim.b[buf].git_status = build(entries, r:head())
    vim.b[buf].git_status_string = render(entries)
end

local enabled = false

function M.enable()
    if enabled then
        return
    end
    enabled = true
    repo.on("refresh", function(r)
        for buf in pairs(r.buffers) do
            if vim.api.nvim_buf_is_loaded(buf) then
                update_buf(buf, r)
            end
        end
        vim.cmd.redrawstatus({ bang = true })
    end)
    vim.api.nvim_create_autocmd("BufWinEnter", {
        group = vim.api.nvim_create_augroup(
            "ow.git.statusline",
            { clear = true }
        ),
        callback = function(args)
            update_buf(args.buf, nil)
        end,
    })
    for _, buf in ipairs(vim.api.nvim_list_bufs()) do
        if vim.api.nvim_buf_is_loaded(buf) then
            update_buf(buf, nil)
        end
    end
end

return M