-- 2
DO $$
DECLARE
    a INT := 0;
    b INT := 1;
    c INT := 1;
    n INT := 7;
BEGIN
    for i in 2..n loop
        c = a + b;
        a = b;
        b = c;
    end loop;
    raise notice '%', c;
END;
$$ LANGUAGE plpgsql;

-- 3
CREATE OR REPLACE FUNCTION fibonacci(n INT)
RETURNS INT AS $$ 
DECLARE
    a INT := 0;
    b INT := 1;
    c INT := 1;
BEGIN
    if n = 0 then
        return 0;
    end if;
    for i in 2..n loop
        c = a + b;
        a = b;
        b = c;
    end loop;
    return c;
END;
$$ LANGUAGE plpgsql;

-- 4
SELECT fibonacci(0); -- 0
SELECT fibonacci(1); -- 1
SELECT fibonacci(2); -- 1
SELECT fibonacci(10); -- 55

-- 5
--DROP FUNCTION IF EXISTS nb_athletes;
CREATE OR REPLACE FUNCTION nb_athletes(code_pays pays.code%TYPE)
RETURNS INT AS $$ 
BEGIN
    return (
        SELECT COUNT(*)
        FROM athlete
        WHERE pays = code_pays
    );
END;
$$ LANGUAGE plpgsql;

-- 6
SELECT nb_athletes('FRA');

-- 7
SELECT p.code, p.nom
FROM athlete a
INNER JOIN pays p ON p.code = a.pays
GROUP BY p.code
HAVING COUNT(*) > nb_athletes('FRA');

-- 8
CREATE OR REPLACE FUNCTION epr(nom_discipline discipline.nom%TYPE, date DATE)
RETURNS TABLE (code epreuve.code%TYPE, nom epreuve.nom%TYPE) AS $$
BEGIN
    return query
        SELECT e.code, e.nom
        FROM epreuve e
        WHERE e.discipl = (
            SELECT d.code FROM discipline d WHERE d.nom = nom_discipline
        ) AND dateE = date;
END;
$$ LANGUAGE plpgsql;

-- 9
SELECT epr('Athletics', '2021-08-03');

-- 10
UPDATE epreuve SET dateE = dateE+1 WHERE code IN (SELECT code FROM epr('Equestrian', '2021-08-02'));

-- 11
CREATE OR REPLACE FUNCTION pratique(code_athlete athlete.code%TYPE)
RETURNS discipline.nom%TYPE AS $$
DECLARE
    res discipline.nom%TYPE;
BEGIN
    SELECT d.nom INTO STRICT res FROM pratiquer p
    INNER JOIN discipline d ON d.code = p.discipl
    WHERE p.athlete = code_athlete;
    return res;
EXCEPTION
    WHEN TOO_MANY_ROWS THEN
        RAISE EXCEPTION 'L''athlète % pratique plusieurs sports.', code_athlete;
    WHEN NO_DATA_FOUND THEN
        RAISE EXCEPTION 'Athlète % inconnu.', code_athlete;
END;
$$ LANGUAGE plpgsql;

-- 12
SELECT pratique(
    (
        SELECT code FROM athlete WHERE prenom = 'Earvin' AND nom = upper('Ngapeth')
    )
);

-- 13
SELECT pratique(
    (
        SELECT code FROM athlete WHERE prenom = 'Lotte' AND nom = upper('Kopecky')
    )
);

-- 14
SELECT pratique('B01');

-- 15
CREATE OR REPLACE FUNCTION medailles(code_pays pays.code%TYPE)
RETURNS FLOAT AS $$
DECLARE
    total_athletes INT;
    athletes_medailles INT;
BEGIN
    SELECT COUNT(*) INTO total_athletes
    FROM athlete
    WHERE pays = code_pays;

    IF total_athletes = 0 THEN
        RAISE EXCEPTION 'Le pays [%] % n''a pas d''athlète.', code_pays, (SELECT nom FROM pays WHERE code = code_pays);
    END IF;

    SELECT COUNT(DISTINCT r.athlete) INTO athletes_medailles
    FROM resultat r
    INNER JOIN athlete a ON a.code = r.athlete
    WHERE a.pays = code_pays;
    return athletes_medailles::FLOAT / total_athletes;
END;
$$ LANGUAGE plpgsql;

-- 16
SELECT medailles(
    (
        SELECT code FROM pays WHERE nom = 'France'
    )
);

-- 17
SELECT medailles(
    (
        SELECT code FROM pays WHERE nom = 'URSS'
    )
);

-- 18
SELECT p.nom, ROUND((medailles(p.code) * 100)::numeric, 2) medailles
FROM resultat r
INNER JOIN athlete a ON a.code = r.athlete
INNER JOIN pays p ON p.code = a.pays
GROUP BY p.code
ORDER BY 2 DESC;

-- 19
--DROP FUNCTION IF EXISTS ageMoy_V1;
CREATE OR REPLACE FUNCTION ageMoy_V1(code_pays pays.code%TYPE)
RETURNS FLOAT AS $$ 
BEGIN
    return (
        SELECT AVG(CURRENT_DATE - dateNaiss) / 365.2422
        FROM athlete
        WHERE pays = code_pays
    );
END;
$$ LANGUAGE plpgsql;

-- 20
/*CREATE OR REPLACE FUNCTION ageMoy_V2(code_pays pays.code%TYPE)
RETURNS FLOAT AS $$
DECLARE
    total INT := 0;
    nb INT := 0;
    r athlete%rowtype;
BEGIN
    for r in
        SELECT * FROM athlete WHERE pays = code_pays AND dateNaiss IS NOT NULL
    loop
        total = (CURRENT_DATE - r.dateNaiss) + total;
        nb = nb + 1;
    end loop;
    return total::FLOAT / nb / 365.2422;
END;
$$ LANGUAGE plpgsql;*/
DROP FUNCTION IF EXISTS ageMoy_V2;
CREATE OR REPLACE FUNCTION ageMoy_V2(code_pays pays.code%TYPE)
RETURNS FLOAT AS $$
DECLARE
    i INT;
    fin INT;
    total INT := 0;
    nb INT := 0;
    date_naiss athlete.dateNaiss%TYPE;
BEGIN
    -- Oui.
    SELECT SUBSTR(MIN(code), 2)::int INTO i FROM athlete WHERE pays = code_pays;
    SELECT SUBSTR(MAX(code), 2)::int INTO fin FROM athlete WHERE pays = code_pays;

    if i IS NULL then
        return 0;
    end if;

    -- Teste pour chaque code possible
    while i <= fin loop
        SELECT dateNaiss INTO date_naiss FROM athlete WHERE code = to_char(i, 'FMA00000');
        if date_naiss IS NOT NULL then
            total = (CURRENT_DATE - date_naiss) + total;
            nb = nb + 1;
        end if;
        i = i + 1;
    end loop;

    if nb = 0 then
        return 0;
    end if;

    return total::FLOAT / nb / 365.2422;
END;
$$ LANGUAGE plpgsql;

-- 21
--SELECT ageMoy_V1('FRA') v1, ageMoy_V2('FRA') v2;
--SELECT ageMoy_V1('USA') v1, ageMoy_V2('USA') v2;

-- 22
CREATE OR REPLACE FUNCTION ageMoy_V1(code_pays pays.code%TYPE)
RETURNS FLOAT AS $$ 
BEGIN
    return (
        SELECT COALESCE(AVG(CURRENT_DATE - dateNaiss), 0) / 365.2422
        FROM athlete
        WHERE pays = code_pays AND dateNaiss IS NOT NULL
    );
END;
$$ LANGUAGE plpgsql;

SELECT ageMoy_V1('') v1, ageMoy_V2('') v2;

-- 23
WITH age_moyen AS (
    SELECT nom, ageMoy_V1(code) AS age_moyen FROM pays
) SELECT nom, age_moyen
FROM age_moyen
ORDER BY age_moyen DESC
LIMIT 1;
-- Ou
WITH age_moyen AS (
    SELECT nom, ageMoy_V1(code) AS age_moyen FROM pays
) SELECT nom, age_moyen
FROM age_moyen
WHERE age_moyen = (SELECT MAX(age_moyen) FROM age_moyen);

-- 24
WITH age_moyen AS (
    SELECT nom, ageMoy_V1(code) AS age_moyen FROM pays
) SELECT nom, age_moyen
FROM age_moyen
WHERE age_moyen != 0
ORDER BY age_moyen
LIMIT 1;

-- 25
CREATE OR REPLACE FUNCTION gagner(code_athlete athlete.code%TYPE, couleur_medaille medaille.couleur%TYPE)
RETURNS INT AS $$ 
BEGIN
    return (
        SELECT COUNT(*) FROM resultat WHERE athlete = code_athlete AND medaille = (
            SELECT place FROM medaille WHERE couleur = couleur_medaille
        )
    );
END;
$$ LANGUAGE plpgsql;

-- 26
SELECT gagner(
    (SELECT code FROM athlete WHERE prenom = 'Teddy' AND nom = 'RINER'),
    'Or'
) medailles_or, gagner(
    (SELECT code FROM athlete WHERE prenom = 'Teddy' AND nom = 'RINER'),
    'Argent'
) medailles_argent, gagner(
    (SELECT code FROM athlete WHERE prenom = 'Teddy' AND nom = 'RINER'),
    'Bronze'
) medailles_bronze;

-- 27
CREATE TABLE IF NOT EXISTS resultat_fr (
    code CHAR(6) PRIMARY KEY REFERENCES athlete(code),
    nom VARCHAR(40) NOT NULL,
    prenom VARCHAR(40) NOT NULL,
    dateNaiss DATE,
    nb_or INT DEFAULT 0,
    nb_argent INT DEFAULT 0,
    nb_bronze INT DEFAULT 0
);

-- 28
INSERT INTO resultat_fr
SELECT code, nom, prenom, dateNaiss, gagner(code, 'Or'), gagner(code, 'Argent'), gagner(code, 'Bronze')
FROM athlete
WHERE pays = (SELECT code FROM pays WHERE nom = 'France');

-- 29
SELECT * FROM resultat_fr ORDER BY (nb_or + nb_argent + nb_bronze) DESC, dateNaiss;