import sqlite3
import os
from datetime import datetime

class DataStore:
    def __init__(self, dbfile):
        if not os.path.exists(dbfile):
            self.createdb(dbfile)
        self.conn = sqlite3.connect(dbfile)

    def __del__(self):
        self.conn.close()

    def createdb(self, dbfile):
        conn = sqlite3.connect(dbfile)
        c = conn.cursor()
        c.execute('''
CREATE TABLE projects (
    id INTEGER PRIMARY KEY,
    name TEXT
)''')
        c.execute('''
CREATE TABLE tasks (
    id INTEGER PRIMARY KEY,
    projectid INTEGER,
    name TEXT,
    UNIQUE (projectid, name),
    FOREIGN KEY (projectid) REFERENCES projects(id)
)''')
        c.execute('''
CREATE TABLE hours (
    date TEXT,
    taskid INTEGER,
    seconds INTEGER,
    PRIMARY KEY (date, taskid),
    FOREIGN KEY (taskid) REFERENCES tasks(id)
)''')
        conn.commit()
        c.close()
        conn.close()

    def getProjects(self):
        c = self.conn.cursor()
        c.execute('''
SELECT id, name
FROM projects
''')
        projects = {}
        for row in c:
            projects[row[0]] = row[1]
        c.close()
        self.conn.commit()
        return projects

    def getTasks(self, projectid):
        c = self.conn.cursor()
        c.execute('''
SELECT id, name
FROM tasks
WHERE projectid = ?
''', (projectid,))
        tasks = {}
        for row in c:
            tasks[row[0]] = row[1]
        c.close()
        self.conn.commit()
        return tasks

    def createProject(self, projectname):
        c = self.conn.cursor()
        projects = self.getProjects()
        if projectname in projects.values():
            return 0
        nextid = self.getNextId('projects')
        c.execute('''
INSERT INTO projects (id, name)
VALUES (?, ?)
''', (nextid, projectname))
        c.close()
        self.conn.commit()
        return nextid

    def createTask(self, projectid, taskname):
        c = self.conn.cursor()
        tasks = self.getTasks(projectid)
        if taskname in tasks.values():
            return False
        projects = self.getProjects()
        if not projectid in projects:
            return False
        nextid = self.getNextId('tasks')
        c.execute('''
INSERT INTO tasks (id, projectid, name)
VALUES (?, ?, ?)
''', (nextid, projectid, taskname))
        c.close()
        self.conn.commit()
        return True

    def getNextId(self, table):
        c = self.conn.cursor()
        nextid = 1
        c.execute('''
SELECT MAX(id)
FROM %s
''' % table)
        for row in c:
            if row[0]:
                nextid = row[0] + 1
        c.close()
        return nextid

    def getDailyHours(self, date):
        hours = {}
        c = self.conn.cursor()
        c.execute('''
SELECT projects.id, tasks.id, hours.seconds
FROM projects, tasks, hours
WHERE hours.date = ?
  AND hours.taskid = tasks.id
  AND tasks.projectid = projects.id
''', (date,))
        for row in c:
            pid, tid, secs = row
            if not pid in hours:
                hours[pid] = {}
            if not tid in hours[pid]:
                hours[pid] = {}
            hours[pid][tid] = secs
        c.close()
        self.conn.commit()
        return hours

    def getProjectDailyHours(self, date):
        hours = {}
        c = self.conn.cursor()
        c.execute('''
SELECT projects.id, SUM(hours.seconds)
FROM projects, tasks, hours
WHERE hours.date = ?
  AND hours.taskid = tasks.id
  AND tasks.projectid = projects.id
GROUP BY projects.id
''', (date,))
        for row in c:
            pid, tid, secs = row
            if not pid in hours:
                hours[pid] = {}
            if not tid in hours[pid]:
                hours[pid] = {}
            hours[pid][tid] = secs
        c.close()
        self.conn.commit()
        return hours