mod query_parser;

use std::fs;
use std::path::PathBuf;
use std::str;

use failure::{ Error, Fail };
use serde::ser::{ Serialize, SerializeMap, SerializeSeq, Serializer };
use structopt::StructOpt;
use toml_edit::{ value, Document, Item, Table, Value };

use query_parser::{ parse_query, Query, TpathSegment };

// TODO : Get more of the description in the README into the CLI help.
#[ derive( StructOpt ) ]
#[ structopt( about ) ]
enum Args
{
  /// Print some data from the file
  Get
  {
    /// Path to the TOML file to read
    #[ structopt( parse( from_os_str ) ) ]
    path : PathBuf,
    /// Query within the TOML data ( e.g. `dependencies.serde`, `foo[ 0 ].bar` )
    query : String,
    #[ structopt( flatten ) ]
    opts : GetOpts,
  },
  /// Edit the file to set some data ( currently, just print modified version )
  Set
  {
    /// Path to the TOML file to read
    #[ structopt( parse( from_os_str ) ) ]
    path : PathBuf,
    /// Query within the TOML data ( e.g. `dependencies.serde`, `foo[ 0 ].bar` )
    query : String,
    /// String value to place at the given spot ( bool, array, etc. are TODO )
    value_str : String, // TODO more forms
  },
  // TODO : append/add ( name TBD )
 }

#[ derive( StructOpt ) ]
struct GetOpts
{
  /// Print as a TOML fragment ( default : print as JSON )
  #[ structopt( long ) ]
  output_toml : bool,
  #[ structopt( short, long, default_value = "json" ) ]
  format : String,
}

#[ derive( Debug, Fail ) ]
enum CliError
{
  #[ fail( display = "bad query" ) ]
  BadQuery(),
  #[ fail( display = "numeric index into non-array" ) ]
  NotArray(),
  #[ fail( display = "array index out of bounds" ) ]
  ArrayIndexOob(),
}

fn main() -> Result<(), Error>
{
  let args = Args::from_args();
  match args
  {
    Args::Get
    {
      path,
      query,
      opts
    } => get( path, &query, opts )?,
    Args::Set
    {
      path,
      query,
      value_str,
    } => set( path, &query, &value_str )?,
  }
  Ok( () )
}

fn read_parse( path : PathBuf ) -> Result<Document, Error>
{
  // TODO : better report errors like ENOENT
  let data = fs::read( path )?;
  let data = str::from_utf8( &data )?;
  Ok( data.parse::<Document>()? )
}

fn get( path : PathBuf, query : &str, opts : GetOpts ) -> Result<(), Error>
{
  let tpath = parse_query_cli( query )?.0;
  let doc = read_parse( path )?;

  if opts.output_toml
  {
    print_toml_fragment( &doc, &tpath );
  } else {
    let item = walk_tpath( &doc.root, &tpath );
    // TODO : support shell-friendly output like `jq -r`
    if opts.format == "yaml"
    {
      let output = serde_yaml::to_string( &JsonItem( item ) )?;
      println!( "{}", output.replace( "---\n", "" ).trim() );
    }
    else
    {
      println!( "{}", serde_json::to_string( &JsonItem( item ) )? );
    }
  }
  Ok( () )
}

fn print_toml_fragment( doc : &Document, tpath : &[ TpathSegment ] )
{
  use TpathSegment::{ Name, Num };

  let mut item = &doc.root;
  let mut breadcrumbs = vec![];
  for seg in tpath
  {
    breadcrumbs.push( ( item, seg ) );
    match seg
    {
      Name( n ) => item = &item[ n ],
      Num( n ) => item = &item[ n ],
    }
  }

  let mut item = item.clone();
  while let Some( ( parent, seg ) ) = breadcrumbs.pop()
  {
    match ( seg, parent )
    {
      ( Name( n ), Item::Table( t ) ) =>
      {
        // TODO clean up all this copying; may need more from toml_edit API
        let mut next = t.clone();
        while !next.is_empty()
        {
          let ( k, _ ) = next.iter().next().unwrap();
          let k = String::from( k );
          next.remove( &k );
        }
        next[ n ] = item;
        item = Item::Table( next );
      }
      ( Num( _ ), Item::ArrayOfTables( a ) ) =>
      {
        // TODO clean up this copying too
        let mut next = a.clone();
        next.clear();
        match item
        {
          Item::Table( t ) => { next.append( t ); }
          _ => panic!( "malformed TOML parse-tree" ),
        }
        item = Item::ArrayOfTables( next );
      }
      _ => panic!( "UNIMPLEMENTED : --output-toml inside inline data" ), // TODO
    }
  }
  let mut doc = Document::new();
  doc.root = item;
  print!( "{}", doc.to_string() );
}

fn set( path : PathBuf, query : &str, value_str : &str ) -> Result<(), Error>
{
  let tpath = parse_query_cli( query )?.0;
  let mut doc = read_parse( path )?;

  let mut item = &mut doc.root;
  let mut already_inline = false;
  let mut tpath = &tpath[ .. ];
  use TpathSegment::{ Name, Num };
  while let Some( seg ) = tpath.first()
  {
    tpath = &tpath[ 1.. ]; // TODO simplify to `for`, unless end up needing a tail
    match seg
    {
      Num( n ) =>
      {
        let len = match &item
        {
          Item::ArrayOfTables( a ) => a.len(),
          Item::Value( Value::Array( a ) ) => a.len(),
          _ => return Err( CliError::NotArray().into() ),
        };
        if n >= &len
        {
          return Err( CliError::ArrayIndexOob().into() );
        }
        if let Item::Value( _ ) = &item
        {
          already_inline = true
        }
        item = &mut item[ n ];
      }
      Name( n ) =>
      {
        match &item
        {
          Item::Table( _ ) => (),
          Item::Value( Value::InlineTable( _ ) ) => already_inline = true,
          // TODO make this more directly construct the new, inner part?
          _ =>
          {
            *item = if already_inline
            {
              Item::Value( Value::InlineTable( Default::default() ) )
            }
            else
            {
              Item::Table( Table::new() )
            }
          }
        };
        item = &mut item[ n ];
      }
    }
  }
  *item = value( value_str );

  // TODO actually write back
  print!( "{}", doc.to_string() );
  Ok( () )
}

fn parse_query_cli( query : &str ) -> Result<Query, CliError>
{
  parse_query( query ).map_err( | _err |
  {
    CliError::BadQuery() // TODO : specific message
  })
}

fn walk_tpath<'a>( mut item : &'a toml_edit::Item, tpath : &[ TpathSegment ] ) -> &'a toml_edit::Item
{
  use TpathSegment::{ Name, Num };
  for seg in tpath
  {
    match seg
    {
      Name( n ) => item = &item[ n ],
      Num( n ) => item = &item[ n ],
    }
  }
  item
}

// TODO Can we do newtypes more cleanly than this?
struct JsonItem<'a>( &'a toml_edit::Item );

impl Serialize for JsonItem<'_>
{
  fn serialize<S>( &self, serializer : S ) -> Result<S::Ok, S::Error>
  where
    S : Serializer,
  {
    match self.0
    {
      Item::Value( v ) => JsonValue( v ).serialize( serializer ),
      Item::Table( t ) => JsonTable( t ).serialize( serializer ),
      Item::ArrayOfTables( a ) =>
      {
        let mut seq = serializer.serialize_seq( Some( a.len() ) )?;
        for t in a.iter()
        {
          seq.serialize_element( &JsonTable( t ) )?;
        }
        seq.end()
      }
      Item::None => serializer.serialize_none(),
    }
  }
}

struct JsonTable<'a>( &'a toml_edit::Table );

impl Serialize for JsonTable<'_>
{
  fn serialize<S>( &self, serializer : S ) -> Result<S::Ok, S::Error>
  where
    S : Serializer,
  {
    let mut map = serializer.serialize_map( Some( self.0.len() ) )?;
    for ( k, v ) in self.0.iter()
    {
      map.serialize_entry( k, &JsonItem( v ) )?;
    }
    map.end()
  }
}

struct JsonValue<'a>( &'a toml_edit::Value );

impl Serialize for JsonValue<'_>
{
  fn serialize<S>( &self, serializer : S ) -> Result<S::Ok, S::Error>
  where
    S : Serializer,
  {
    if let Some( v ) = self.0.as_integer()
    {
      v.serialize( serializer )
    }
    else if let Some( v ) = self.0.as_float()
    {
      v.serialize( serializer )
    }
    else if let Some( v ) = self.0.as_bool()
    {
      v.serialize( serializer )
    }
    else if let Some( v ) = self.0.as_str()
    {
      v.serialize( serializer )
    }
    else if self.0.as_date_time().is_some()
    {
      "UNIMPLEMENTED : DateTime".serialize( serializer ) // TODO
    }
    else if let Some( arr ) = self.0.as_array()
    {
      let mut seq = serializer.serialize_seq( Some( arr.len() ) )?;
      for e in arr.iter()
      {
        seq.serialize_element( &JsonValue( e ) )?;
      }
      seq.end()
    } else if let Some( t ) = self.0.as_inline_table()
    {
      let mut map = serializer.serialize_map( Some( t.len() ) )?;
      for ( k, v ) in t.iter()
      {
        map.serialize_entry( k, &JsonValue( v ) )?;
      }
      map.end()
    }
    else
    {
      panic!( "unknown variant of toml_edit::Value" );
    }
  }
}