local t = require("test")
local util = require("git.util")

local function fresh_buf()
    local buf = vim.api.nvim_create_buf(false, true)
    t.defer(function()
        pcall(vim.api.nvim_buf_delete, buf, { force = true })
    end)
    return buf
end

t.test("set_buf_lines preserves modifiable=false", function()
    local buf = fresh_buf()
    vim.bo[buf].modifiable = false
    util.set_buf_lines(buf, 0, -1, { "a", "b", "c" })
    t.eq(
        vim.api.nvim_buf_get_lines(buf, 0, -1, false),
        { "a", "b", "c" },
        "lines should be replaced"
    )
    t.falsy(vim.bo[buf].modifiable, "modifiable should stay false")
    t.falsy(vim.bo[buf].modified, "modified should be cleared")
end)

t.test("set_buf_lines preserves modifiable=true", function()
    local buf = fresh_buf()
    vim.bo[buf].modifiable = true
    util.set_buf_lines(buf, 0, -1, { "a", "b" })
    t.truthy(vim.bo[buf].modifiable, "modifiable should stay true")
    t.falsy(vim.bo[buf].modified, "modified should be cleared")
end)

t.test("set_buf_lines partial range update", function()
    local buf = fresh_buf()
    vim.api.nvim_buf_set_lines(buf, 0, -1, false, { "a", "b", "c", "d" })
    util.set_buf_lines(buf, 1, 3, { "X", "Y", "Z" })
    t.eq(
        vim.api.nvim_buf_get_lines(buf, 0, -1, false),
        { "a", "X", "Y", "Z", "d" },
        "lines [1, 3) should be replaced"
    )
end)

t.test("set_buf_lines errors on out-of-bounds (strict_indexing)", function()
    local buf = fresh_buf()
    vim.api.nvim_buf_set_lines(buf, 0, -1, false, { "a", "b" })
    local ok = pcall(util.set_buf_lines, buf, 100, 200, { "x" })
    t.falsy(ok, "out-of-bounds index should error")
end)