# `ExQuality.Init.DepInstaller`
[🔗](https://github.com/riddler/ex_quality/blob/v0.16.0/lib/ex_quality/init/dep_installer.ex#L1)

Adds dependencies to mix.exs programmatically.

Uses line-based insertion to preserve formatting and comments.
Validates syntax after editing to ensure correctness.

# `add_dependencies`

```elixir
@spec add_dependencies(%{required(atom()) => {atom(), String.t()}}) ::
  :ok | {:error, String.t()}
```

Adds dependencies to mix.exs.

Inserts new deps immediately after :ex_quality dependency (or at end of deps list).
Creates a backup at mix.exs.backup before modifying.

## Returns

- `:ok` on success
- `{:error, reason}` on failure

# `build_dep_lines`

```elixir
@spec build_dep_lines(%{required(atom()) => {atom(), String.t()}}, String.t()) :: [
  String.t()
]
```

Builds dependency lines to insert.

Uses recommended installation options from each tool's documentation.

Format:
    {:credo, "~> 1.7", only: [:dev, :test], runtime: false},
    {:dialyxir, "~> 1.4", only: [:dev], runtime: false},
    {:excoveralls, "~> 0.18", only: :test},

# `extract_indent`

```elixir
@spec extract_indent(String.t()) :: String.t()
```

Extracts indentation from a line.

## Examples

    extract_indent("      {:credo, "~> 1.7"}")
    #=> "      "

    extract_indent("\t\t{:dialyxir, "~> 1.4"}")
    #=> "\t\t"

# `find_insertion_point`

```elixir
@spec find_insertion_point(String.t()) ::
  {:ok, non_neg_integer(), String.t()} | {:error, String.t()}
```

Finds the line number where new deps should be inserted.

## Strategy

1. Look for :ex_quality dependency line
2. Insert immediately BEFORE it (so new deps have commas and ex_quality comma is optional)
3. If not found, insert at end of deps function (before closing bracket)

## Returns

- `{:ok, line_number, indentation_string}` on success
- `{:error, reason}` on failure

# `insert_lines`

```elixir
@spec insert_lines(String.t(), non_neg_integer(), [String.t()]) :: String.t()
```

Inserts lines into content at the specified line number.

## Examples

    insert_lines("line1\nline2\nline3", 2, ["new1", "new2"])
    #=> "line1\nline2\nnew1\nnew2\nline3"

---

*Consult [api-reference.md](api-reference.md) for complete listing*