Javascript tobuild GoogleChart basedon Spreadsheet

We look for the js dev of a feature around Google Chart and Google Spreadsheet.
We want a web client js script to build a Google Chart, based on a Google Spreadsheet stored in a Google Drive.

Scenario A
- I am on the web page of the application; there is a button "new chart"; I click on it.
- Then a Google File Picker popup opens to help me to select the Google Spreadsheet containing the data I want to build a chart with.
- After selecting one Spreadsheet, a Google Chart Editor popup opens (based on the selected Spreadsheet), to help me to select my data (sheet and cells) and to configure my chart.
- After validation, my chart appears in the web page under the button "new chart"; three buttons "delete", "update chart" and "update data" appear also.

Scenario B
- I click on the button "update chart" near my chart.
- A Google Chart Editor popup opens (based on the chart on the web page), to help me to adjust my chart.
- After validation, my updated chart appears in the web page.

Scenario C
- I click on the button "update data" near my chart.
- A custom popup opens (based on the selected Spreadsheet, sheet and cells), to help me to adjust the data involved in this chart.
- After validation, my chart is refreshed with the new data.

Scenario D
- I click on the button "delete" near my chart.
- A custom popup asks me to confirm the deletion.
- If yes, the chart and the 3 buttons disappear of the web page

Google FilePicker API : [URL visible pour les membres Pro]
Google Chart Editor : [URL visible pour les membres Pro]#google_visualization_charteditor

Thanks to deliver the code and a demo on Google App Engine.