(** Init script for the SQLite database. **)
let inits = "\
	DROP TABLE IF EXISTS elements; \
	DROP TABLE IF EXISTS cache; \
	CREATE TABLE elements ( \
		num INTEGER PRIMARY KEY NOT NULL, \
		symb TEXT UNIQUE NOT NULL, \
		name TEXT UNIQUE NOT NULL, mass FLOAT, \
		cpk_color TEXT, e_config TEXT, e_neg FLOAT, rad FLOAT, \
		ionization_e FLOAT, e_affinity FLOAT, \
		oxidation TEXT, state TEXT, \
		melting FLOAT, boiling FLOAT, density FLOAT, \
		block TEXT, discovered INTEGER) WITHOUT ROWID; \
	CREATE TABLE cache ( \
		name TEXT PRIMARY KEY NOT NULL, \
		dat BLOB NOT NULL) WITHOUT ROWID; \
"

(** Converts the column data in the PubChem JSON file to
    a string option array. *)
let toarr json = let open Yojson.Basic.Util in
	json |> member "Table" |> member "Columns" |> member "Column"
	|> to_list |> filter_string |> Array.of_list 
(** The PubChem JSON file is compressed by keeping all key values in
    a single array at the top called [Column]. *)

(** Ignores all rows or throws an exception, then resets [stmt]. *)
let allstep stmt = let open Sqlite3 in
	let rec f = function
	| Rc.ROW -> f (step stmt)
	| x -> Rc.check x
	in
	f (step stmt);
	reset stmt |> Rc.check

(** Initializes [db] from [json]. *)
let makedb db json = let open Sqlite3
	in let () = exec db inits |> Rc.check
	in let symbs = ref []
	in let names = ref []
	in let colarr = toarr json
	in let stmt = "INSERT INTO elements \
		(num, symb, name, mass, cpk_color, e_config, e_neg, \
		rad, ionization_e, e_affinity, oxidation, state, \
		melting, boiling, density, block, discovered) VALUES \
		(:AtomicNumber, :Symbol, :Name, :AtomicMass, \
		:CPKHexColor, :ElectronConfiguration, \
		:Electronegativity, :AtomicRadius, :IonizationEnergy, \
		:ElectronAffinity, :OxidationStates, :StandardState, \
		:MeltingPoint, :BoilingPoint, :Density, :GroupBlock, \
		:YearDiscovered);"
	|> prepare db

	in let binds stmt s v = bind_name stmt (":" ^ s) v |> Rc.check

	(* Bind each column name. In SQLite3 the leading ":" is part
	of the named parameter. *)
	in let prep i x =
		(match colarr.(i) with
		| "Symbol" -> symbs := (x,None)::!symbs
		| "Name" -> names := (x,None)::!names
		| _ -> ()
		);
		binds stmt colarr.(i)
		    (if x = "" then Data.NULL else Data.TEXT x)

	(* Cache fuzzy matching automaton. *)
	in let do_model name vals =
		let stmt = "INSERT INTO cache VALUES (:name, :cache);"
		|> prepare db
		in let open Batch_jaro_winkler
		in let model = build_exportable_model
			~encoding:Encoding.UTF8 vals
		in
		binds stmt "name" (Data.TEXT name);
		binds stmt "cache" (Data.TEXT model);
		allstep stmt;
		finalize stmt |> Rc.check

	in let open Yojson.Basic.Util
	in let access_data x = x |> member "Cell" |> to_list
		|> filter_string |> List.iteri prep;
		allstep stmt
	in json |> member "Table" |> member "Row" |> to_list
		|> List.iter access_data;
		finalize stmt |> Rc.check;
	do_model "symbs" !symbs;
	do_model "names" !names